As a recent owner of this, upgrading from my 6300 which I love, I'm so pleased I waited for the release of this phone.
The display does go into sleep quickly, which I think is a little odd to be fair, but not an inconvenience at all.
The display, sound and user menus are really quite excellent. Trouble is, as it's all chrome, I keep wiping my dirty fingerprints off the case. More a problem with my hands than the phone though.
Sitting side by side with my 6300 I can say that the keys on the 6700 are actually larger than the 6300. They are a different design, not being separate keys, but that's a case of getting used to it I suspect.
It's a great phone that does what a phone is supposed to do.