well, HTC HD2 is a really large phone, (but with a large screen too). when im holding it, i always thing that i might drop it..

-no divx and xvid support but not really a big deal for that.
-flash on browser seems quite below par.

-it has a snap dragon processor.
-i can say better audio quality than n900.
-very good opera browser, IMHO,
-good video playback.

that is all i can say, its not even a month when i use an HTC HD2

you can learn more by browsing gsmarena.com

just search the phone, and click compare if you are between two phones.

EDIT: oh yes! it is unlocked