I agree the Apple TV is restrictive on filetypes (unless you have a version 2 box that can be easily jailbroken for xmbc/plex) but the WDTV is essentially a file browser that happens to play all manner of video codecs.
Unless you manually grab the .nfo/.tbn for each video you stream through a WDTV, the box itself won't automatically pull the info down from IMDB/TVDB.
How does the WD TV handle TV seasons?
It doesn't do any fancy media library-style grouping of files at all - you just get a list of available files in a shared folder.