[UPDATE: also read my updated post on the iPhone 3GS]
I spent the week in Silicon Valley for a bunch of meetings, and I've been disappointed with the voice quality of the iPhone (esp. recently), so I decided to carry both it and my E71. In addition, I now have my work email, contacts, calendar, and corporate directory on the E71. For a bit of history, I've been using the iPhone for more than a year, and haven't used the E71 seriously until now.
What follows are a bunch of rough categories and a "winner" in each, followed by thoughts and opinions.
Voice quality: E71, by far. This is the iPhone's primary achilles heel, the voice quality is brittle and irritating, to the point that I cannot listen to it for any length of time. Worse, people frequently have a hard time understanding me. The phone simply needs EQ and a mic sensitivity adjustment, preferably exposed to the user (in some idiot-proof way). In contrast, the E71 has probably the best voice quality of any mobile I've used (and I've used quite a few). At least on par with the best. I have no problem listening to the other party for significant lengths of time, and I have yet to encounter irritating sound, even from an iPhone on the other end.
Responsiveness: E71. iPhone 2.0 came with a lot of new features, but also what comes across as a fair bit of heft. Everything is slower, ranging from just a little in many instances to quite a lot in a few (the keyboard is VERY slow now, almost without exception). Even the "just a little slower" instances are significant, though, because of the nature of the UI. If you touch a button and can't feel a response, the way you know it worked is because it does what you told it immediately. Apple has broken that in iPhone 2.0 and thus the gorgeous UI feels sluggish and buggy. Again, the E71 is a marked contrast, being one of the most responsive phones I've used and by far the most responsive S60 Nokia I've ever seen.
Web: iPhone. The iPhone browser is beautiful, very easy to use, and its understanding of column layouts and zooming is excellent. Touch dragging, rubber banding, etc. all contribute to a fabulous user experience. The E71 browser is based around the same engine (though probably a little older), but without the touch UI it just isn't the same thing. Having to "fly" the cursor around just sucks.
Email: iPhone, by a little. iPhone's email UI is far superior to the E71 native or Mail for Exchange UIs. However, typing an email on the iPhone is less of a win, and I probably prefer the E71 there (tough choice). The E71's responsiveness is a win here, so iPhone wins by only a little.
Wi-Fi: iPhone. It just works. E71 has the bass-ackwards Access Point system which sucked five years ago and is now totally unacceptable. S60 should be ashamed. Having said that, the 3/3.5G connectivity on E71 is so good, I basically don't use Wi-Fi at all. One ubiquitous data pipe FTW!
Cellular/3G data: E71. 3/3.5G data is fast and responsive on the E71, and the general responsiveness of the device adds to that impression. I have the original iPhone, so I haven't spent a lot of time using the 3G version, but enough to say that I don't find it as reliable and responsive as the E71. Plus the sluggish iPhone UI detracts from the whole experience. Another thing I notice: I always have data on E71, when I may not even have signal on iPhone. Both are on AT&T.
Maps: E71, by far. Strange, huh? I love the iPhone Google Maps app, don't get me wrong, Touching and pinching and all. And Nokia Maps is a suck-fest to put it kindly. But, much to my surprise, Google Maps on the E71 is fantastic! The phone's GPS is extremely responsive and accurate and the Google Maps app ties into it perfectly. Zooming in and out is very fast (just hit 1 or 3) and much more usable while driving (did I say that?) than iPhone's. Perhaps because of the speedy 3G data, the search function seems blazing fast, and very accurate.
Home Screen: E71. It's customizable, with fast access to common features, email summary, broken out "recents" like voicemail, SMS, and missed calls, etc. iPhone is nice, but I get to things I need more quickly on E71.
Contacts: A tossup. iPhone's UI is prettier and easier to manage, by far. Adding contact info is very obvious. E71's UI is more bare-bones and editing contacts is somewhat painful. However, contact search is SO MUCH BETTER on E71. iPhone's search is dreadfully slow, mostly because it takes 5-10 seconds for the keyboard to function. E71's is immediate, and search is available full-time, you don't have to do anything for it to come up. MobileMe syncing is nice on iPhone, though. I have E71 syncing to my MacBook Pro and to Ovi (ovi.com), and it works fine, but it's not as "invisible" as MobileMe, for better or worse.
Calendar: E71, by a little. iPhone is prettier and easier to look at, but otherwise is somewhat sucky. I can create/find/edit meetings and reminders on E71 much more quickly. Defaults are better on E71 too. Again, MobileMe is nice on iPhone.
Typing: A tossup. I type faster on the iPhone, even though its keyboard isn't real. However, sometimes it takes so long for the keyboard to function that I would have been done already on the E71. E71 is fast and consistent, and then there is that thing of having real keys. So it's hard to pick a winner here. If iPhone was as responsive as the E71, it would win hands down.
Local connectivity: E71, by far. Bluetooth 2.0 w/ EDR and a pile of profiles. iPhone supports mono Bluetooth headsets and that's it (um, Apple?).
Tethering: E71, by far. iPhone doesn't tether. Thanks, Apple. E71's excellent 3/3.5G data speed makes this very attractive.
SMS iPhone. iPhone's chat-style SMS interface is truly brilliant. It's SO much better than the traditional one-message-at-a-time interface. MUCH better. Nokia, please copy this, right now. :)
Form factor: A tossup. iPhone is a great fit-in-your-pocket size, has a gorgeous screen, feels good to hold, etc. E71 fits even better, feels equally good to me (except for touching the screen of course, since you don't do that), but has a much smaller screen.
In-call features (e.g. mute): iPhone. Nokia loves to bury these, grrrrr. iPhone wins here. iPhone conferencing works well (if you can stand the voice quality to begin with). In-call keypad is nice, Nokia still keeps the in-call keypress backlog in a dial bubble, which is annoying.
Camera: E71. 3.2MP gives you a lot more blurry pixels than iPhone's 2.0. But the real win here is video, on both sides of the phone! iPhone 3G should've had video. Bleh. E71 wins. Video also means apps like Qik which is very cool IMO.
UPDATED: turns out you have to autofocus the camera manually! Press the '2' button and it will focus, THEN take your pic! Much less blurry!
Media: iPhone, by far. Ummm, ok the Nokia sucks at media. Really, really sucks. iPhone is the best iPod ever (really, not just b/c Steve says so). E71 is pathetic in this category, sorry. iPhone's screen and touch UI just make the difference even more glaring. No contest. iPhone also excels at displaying photos, even if it can't take a decent one on its own.
Applications: iPhone. The iPhone SDK is a joy, lots of good applications exist, they blow away the equivalents on S60 in most cases (Twitter client, for example). Some S60/E71 apps are outstanding (Google Maps), but most are not. The Apple/iTunes ecosystem is very good for applications.
Games: iPhone, by far. Yeah... the iPhone is a standout game platform. Accelerometers plus beautiful 2D plus beautiful 3D plus great SDK => lots of fun games, for cheap. Great game device.
VoIP: E71. iPhone doesn't have it, and won't have it, given the current SDK restrictions. No background apps => no listening for incoming SIP calls. E71 VoIP works well, once configured, but configuring it does suck quite a bit.
It's very hard for me to pick one. I love, almost adore, the iPhone. It has revolutionized the mobile industry. The UI is brilliant and easy. Many things just work. However, it has some very big warts, particularly since the 2.0 release. The #1 problem is voice quality... it's just terrible, worst I've ever heard on a mobile phone. A close second is the very sluggish UI, especially the keyboard. Many times it is nearly unusable, which is shocking considering the iPhone's bread and butter is usability. This is a new "feature" since 2.0, 1.x was much more responsive.
E71 is very fast and very utilitarian. I can get a lot done quickly once I know how. It has much better connectivity than iPhone (the lack of full Bluetooth 2.0 and tethering is ridiculous), it has video, it has a real keyboard (for better or worse), a great home screen, etc. Finally, the E71 is hands down the winner in the "just a phone" category. Contact searching is very fast, voice quality is excellent.
So here's what I want: toss the iPhone, get an iPod touch, use Bluetooth to the E71 to connect anywhere. Oh wait, Apple doesn't do that on iPod touch. GRRRRRR. Thanks, Apple.
I guess if pressed, I would have to take the E71 over the iPhone, as a phone, because it does the basics really well, and I can stand to talk on it for hours. I can sync it, search my contacts very quickly, etc. Texting is more of a chore, but the keyboard is nice, so the actual typing part is good. Everything is anywhere from a little to a lot uglier, but it really works, and the thing is so very responsive. But there's no chance there wouldn't be a least an iPod touch in my other pocket. :) The combo of the two (iPhone and E71) is hard to beat. I basically treat the iPhone as a touch with data.
My last conclusion: Apple must fix their OS. The iPhone would've won out in many categories if it wasn't sluggish and unreliable, especially where the keyboard is concerned. Very frustrating. Apple, fix your phone.
UPDATED: my really last conclusion, I meant to say this in the original post - E71 is definitely more oriented towards phone/mobility geeks than towards the average "just make it work" user. Advanced users will make use of the additional features and will appreciate the snappy UI, and will be better able to overlook or work with the cumbersome S60 OS.