My buddy has a Western Digital WDTV and he's got mixed feelings about it. It worked alright for a long time, but will not play MKVs muxed with the new mkvmerge, which has lately become a hassle, as such a file crashes the whole player. It won't play DTS with his Panasonic surround system (there's some sort of known conflict between the two), but apparently it's supposed to do bitstream passthrough of DTS to a capable receiver. It works pretty good for a $100 player though. His main beef is that Western Digital stops supporting their older models once they come out with a new one, which is a problem with a lot of mainstream products.
I have the original Popcorn Hour A-100 and it still has firmware updates that keep it supporting every new codec I throw at it. You could probably find one of those online for cheap. They have newer models that are a little pricier, but they really are a great, small company owned and operated by true geeks who know their stuff.