I'm one week in to my iPhone 5. Overall, I'd give it a thumbs up.
I upgraded from an iPhone 4, so I was two models back. Significant speed upgrade, I still notice that daily. LOVE that actually.
I get slightly faster downloads on my home wifi which is nice. But the LTE coverage in ATL is good, so I'm now enjoying that in most places and again, another nice speed bost.
Maps, well it hasn't steered me wrong yet, but it has a few friends. I have a backup app loaded just in case, and I can always hit the mobile site version of GoogleMaps if I had to. I will say though, I've used it a few times for driving directions and the turn-by-turn was nice to finally have and handled things really well. My only complaint about it was the voice was set to high as the default, and it was really freaking loud. Toning that down a notch or two made it useable without scaring the piss out of me everytime she said, "Your turn is approaching in 500ft".
I'm a happy iPhone 5 upgrader, and I'd recommend it. Especially if you're already in the iPhone universe, have Apple apps, etc.
The only large drawback right now is the availability of extra charging cables. I probably have half a dozen strategically placed around my home and vehicles, and none of them work now. And the new fangled ones are on backorder, and they're $30 a piece. Annoying, for now. Soon there will be cheaper cables, and the supply will catch up with the demand. It's just annoying to have to think about packing my cable in my laptop bag for the day as I leave if I expect to be on the phone a lot.