To be honest we can't think of a single important format or codec that isn't supported, and indeed the Playon!HD effortlessly handled everything we threw at it, no matter how obscure, or how high or low the quality. Indeed, this is the first media player that played back every single test file in our arsenal without any problems, though Asus' excellent O!Play HDP-R1 HD came awfully close.
This leaves us in a bit of a conundrum. Its unwieldy size, relatively high noise level, slightly awkward (if very well-featured) remote, dated menu system and lack of non-local indexing leave the Playon!HD in a slightly weak position against the cheaper Asus O!Play HDP-R1 HD and indeed Western Digital's WDTV Live HD, both of which offer most of the main features you'd want, in quiet and compact packages. However, the Playon!HD is definitely one of A.C.Ryan's best products yet and its feature-set and file support is pretty much unrivalled by anything currently on the market at this price point.
Unfortunately the best-featured media player to pass through our office is also the biggest and noisiest, with a few interface annoyances to boot. Nonetheless, if you want what A.C.Ryan's Playon!HD has to offer, the bare-bone asking price of £130 seems reasonable.