I get the new dock connector, but it sure will trash a bunch of cool accessories like Swivl and others. I'd hope for a very good reason to break from such a established standard. When they went to the dock connector from firewire, there weren't a zillion things affected like now.
Putting the headphone jack on the bottom initially seems good (my HTC's were like that) but I quickly grew to like the current setup because if you put the phone away, upside down, wouldn't the power button get pressed more often?
Or Docked, I liked that you could have an accessory plugged in, like an external mic.
If they made the unibody from metal maybe it's for heat dissipation with LTE radios. I'm sure the end caps are non-metal solely for antenna performance. I hope these new grills aren't lint magnets as these phones are in pockets much more than iPads or laptops and I could see that as an issue.
All in all, I would have no problem keeping my 4s another year should this be just too much of a change. That would send a message (as if...) and at least let the accessory makers catch up.