I waited a year when the iPhone first shipped. Jumping in at the 2nd phone I've upgraded every other year, taking advantage of the carrier subsidy. I've had the iPhone 5 for a week and I can't recommend it enough.
Some caveats: I'm an Apple fan. I have been for almost 28 years, since the Mac shipped. I use a Mac as my primary computer and the native contact/calendar apps as my defaults. I'm leveraging the synergy of living in a homogenous technological world. It all just works. You may be able to do the same thing in an all Windows world or an all Android world and god bless you. I got a Nexus 7 to try and grok Android and well, it's cute, but I feel like I'm working in a left-handed world as a right-handed person. Doesn't make it bad. Just not for me.So, that said, here's what's cool about the iPhone 5 over the iPhone 4 that I replaced.
• It's fast. The camera, for instance, appears instantly. Pictures save instantly.
• It's fast. LTE has shown up in Sacramento so I can use it here and I got a taste of that speed when I was in the bay area last Saturday.
• Cell service is better. People always complained about the connection when I talked to them on the cell from home. Hasn't come up yet since the 5. Maybe they've given up complaining. But they sound better to me. All that antenna work finally paid off.
• It's weighs less than its predecessor devices and you can feel it. John Gruber went for paragraphs about how 'nice' it feels. It's really that good. I haven't figured out if I'll get a case. I didn't with my 4 and I'm disinclined with the 5.
• The extra height is useful without being cumbersome. I carry the phone in my front pocket and I was wondering if would be able to tell that I had a larger device there. No problem.
• Apple have a problem with Maps. Once in SF it got us around fine. But it had problem doing destination searches and it sent me on a wild goose chase to get to SF from Oakland. But as Tim Cook pointed out, there are alternatives. And Maps isn't that bad. Your mileage may vary.
• Siri's cool. It's been out a while, but I didn't have it on my older phone. She's plenty useful with the faster networking and faster processor of the 5. Not perfect, but I had a perfectly useful text conversation without typing a word.
iOS 6 (save Maps) is nice upgrade. Maybe more a 5.5 than a full dot release, but let's not quibble. Synchronization between my computer and the phone is effectively instant, so a calendar entry made here is updated there before I need it. I've used the reply with message (send a text to a caller when you can't answer rather than just send them to voicemail).
I'm predisposed to buyer's remorse. I have none with this week's new toy.