Well, I have one at home connected to my TV and it's quite nice.
I bought it instead of Media Center PC - since I don't need all the media center functionality (I only want video and sometimes pictures slideshows, while music is handled by SlimPlayer).
It does everything I want - mainly playing streaming video from my "home server", it's much cheaper than any media center PC (it costed me 250 EUR including shipping) and it's completely silent (unlike certain games console).
Few other (random) thoughts:
It plays streaming video just great, I have even tried couple of .MKV HD files and it plays them without any problems (can't comment on picture quality - no HD TV), over the 100Mb Wired LAN from Celeron 2,4GHz Windows XP PC.
I really like the fact that I can rip whole DVD to an ISO image on the PC and I can then play it on my PopCorn with all DVD's functionality (menus, addins...)
It has the ability to connect to some online services, mainly YouTube.
It's interface is not all that good (pretty) but it works, firmware is updated regulary.
I don't have hard disk installed, so I can't try torrent functionality.
Felix, I can't answer your question about displaying LoRes Video on HiRes display as I don't have HD TV at home, only an old 28" CRT. I guess this will have to be my next purchase.
Another review:
http://www.mpcclub.com/modules.php?name=Reviews
(the actual review is in .PDF...)