My short review of ACRyan PlayON HD (POHD), and comparison with new released WDTV Live.
My setup:
ACRyan PlayOn HD connected to my Panna 32in via HDMI, and audio to Creative DDTS-100 via Optical. Use Creative Gigaworks 500 5.1 speaker
Using stock Realtek UI (as seen in Asus Oplay!), this player can play every movie throw into it. Since im only have 5.1 speaker setup, my only concerned audio output format is Dolby Digital and DTS, so Dolby TrueHD and DTS HD is not really my requirement (pls correct me if i'm wrong), and I also didn't have any BD backup or rip in my collection. and since my TV only support up to 720p (1080i doesn't really count), so all my video collection is only up to 720p resolution (save some space!)

So far everything works so well except for the archaic UI. All movie are tested streaming from my networked PC, and no single shuttering or lag happens. Truth to be told, this player makes me to appreciate the beauty of high definition movie, even tho b4 this use my PC to experience it, but the "feel" is different.
then come along WDTV Live. This player touted to have superior PQ than realtek-based player, and can play high reframe video file easily. Plus the UI is far better (which is important bcoz my wife is not as geek as me). So test time!
WDTV Live connected to my Panna 32in via HDMI, and audio to Creative DDTS-100 via Optical. Use Creative Gigaworks 500 5.1 speaker
all movie tested is using AC3 audio codec for 5.1 output, and while all movie correctly identified as Dolby Digital on my ACRyan PlayOn HD, some of these movies can only been outputted by WDTV Live to 2 channel, which is kinda disappointing. PQ for 720p more less same as ACRyan, but on SD video files (I tested Friends), the upscaled SD video on WDTV Live is far inferior than ACRyan's; the blockiness is very obvious, jerky edges all around and the color is too vibrant.
And while watching Friends (which is quite small on file size) halfway, the WDTV Live halt the playback because loosing the network connection, while im yet to experience the same problem on ACRyan (which i owned more than two weeks and all file streamed beautifully).
Youtube support is spot on (WDTV Live), while the support of the internet video is coming soon on ACRyan in upcoming firmware update.
On my judgement, ACryan is far better player than WDTV Live (which also based on previous version of WDTV support by WD itself (which is sporadic at best)).
p/s: sorry for the bad english, pretty sleepy now.