Mine's a 3G, 16 months into an 18 month contract, so I'll be upgrading to a 4G in June. I've had an XDA Mini S and a Nokia N95 before the iPhone, and it's by far and away the most useful piece of electronic whizzyness I've ever used. Sure, the battery gets a hammering, but nobody will own up to saying how crap the N95's battery was, unless you stuck to just making calls. Two hours using the music player would kill the battery, and the GPS about the same. This was regularly highlighted in reviews, and it was true. People bitch about the iPhone being too big as it is; stick a bigger battery in and it would have to be a lot thicker. You can get external battery units, I've got two from Deal Extreme, cost about $20, they're 2400mAh, and they're called iPower. I've got loads of ebooks on mine, using Kindle, ereader, Stanza and 3D Bookcase, I've also got Memory Map Free, with a load of 1:25k OS maps covering Bath to Savernake Forest, and the Forest of Dean, Outdoor South West with the whole of the S/West of England in 1:50k OS, CoPilot Live Turn By Turn mapping, then there's all the other useful apps like Facebook, Shazam, Red Laser, Starwalk, Orange Wednesday, (I'm on O2), Wiki, Google, Find Pubs, iCarRadio, various photo apps...
Frankly, I can't imagine not having it around, I use it all the time, and that has bugger-all to do with ‘novelty’, and everything to do with sheer usability. And the camera is nowhere near as bad as people make out, the 5Mp camera on the N95 was crap, it refused to focus, I spent twenty minutes trying to get a photo of my bike propped up against a tree. It just wouldn't lock on. The iPhone is the perfect snapshot camera, which will upload to Flickr and Facebook easily, which is all you need. If you want more than that, then buy a proper compact like a Lumix TZ-10, for Chris'sake. Nobody ever complained about Instamatic cameras, which is all a phone camera is, and anyone who thinks SE's 12Mp phone camera is going to allow A4 size prints with comparable quality to a camera like my Lumix or D60 is fooling themselves; Wired magazine were quite unimpressed with it. The newer iPhone allows video with in-phone editing, and the 4G will be up to 64Gb, probably with a 5Mp camera as well. Couple that with the iphone's touch screen which is better than pretty much anything else out there, and you have the perfect pocket computer, which is what the iPhone is; you just have to stop thinking of it as a phone.