Build quality: Disappointing. You may have read other reviewers’ concerns on the thin plastic back of the phone, and I agree. The back does seem cheap and ‘plasticky’, and the phone ‘rattles’ on vibrate. The back light can be seen through various cracks on the sides of the front plate.
The keypad: Personally, I like it and had no problem with the bar-type keys. However, the placement of the ‘c’ button makes texting v awkward and uncomfortable.
Design: I love the design. It is sleek, quite slim, and understated.
Nav-key: The D-pad is touch sensitive and works (or is supposed to) in the same way as the iPod click wheel. In reality, this is just a gimmick with little practical use. It simply doesn’t work well enough to make a difference.
Overall: 6/10
I was v excited about this phone, and have waited months beyond my upgrade date for it. But upon delivery, it disappointed me to such a point that I have returned it, cancelled my upgrade and await the release of the 3G iPhone.

Hope this helps.