I've got the next model up (I think) which has a DVD player built in. I've been pretty happy with it for streaming HD (.TS, .AVI). Some things to look out for:-
Doesnt support H.264 which is becoming more prevalent
Doesnt work well over wifi, really needs wired connection
Streaming of photos (slideshows) is useless with larger images and larger numbers of images
No HDMI (component and possibly DVI though (upto 1080i)
Hasnt seen much activity firmware wise which has annoyed some owners
As said, I've been very happy with mine which has been great for streaming TS's. However I am considering changing to something that supports HDMI and H.264.
have a look at the mpcclub website where there are forums discussing all of the above