First impressions are that the phone feels like an expensive phone (unlike the N95 which was marketed as a premium phone but never looked or felt like one). Great build, feels solid in the hand - not that much more weighty than the N95 and for some reason feels less bulky.
Got it in silver (preferred the black but CPW do it in silver only) which actually looks very good and understated (which I like).
Getting used to the keyboard and the sliding mechanism is top drawer!
Going from Portrait to landscape is pretty quick to be fair (no perceptible delay which is great). The Panels have lag but not so much that it would bother me. The radio is excellent as is the Spb Panel which in truth is a must as the other SE panels would get on my nerves after a while. Synching was a cinch on Vista. The phone is incredibly fast for WinMo phone and switching between apps is pretty fast.
The screen is absolutely superb and was the real reason why I chose it over the Omnia. Navigating around the phone and WinMo in general looks quality and I swore after the HTC Wizard my next WinMo device would have a Hi-Res screen.
Screen is very responsive (it still has the plastic protective sheet on until I get a screen protector!) and inspite of the recessed screen I can get to the corners to close apps etc.
Multimedia wise it is excellent - got Coreplayer which handles videos etc. really well.
As for form factor - well for me it is perfect - large screen and yet the phone is not too big and still feels like a phone i.e. you don't feel awkward putting it to your ear whilst getting a call which for me was very important. That was what put me off the HTC Touch HD (and iPhone) which is an otherwise excellent phone.
More impressions later as I get to play more and more. Take heed of the sticky in this forum about Paul's must have apps - excellent choices!