I absolutely love openelec!
My HTPC is an Asrock ION 330HT, and I just wan it work. It does nothing more than being an HTPC, no file serving, no downloading, nothing, just pure HTPC. And for that, I think Openelec is unbeatable. You install and configure it, then you forget about. You can edit a bunch of things (like samba shares, the remote keymaps and a few other things) using their Configuration shared folder. There's also sFTP enabled, so that you can have access to the whole filesystem from another PC.
About HD audio, yeah, that's one thing missing. But to be fair, it's missing altogether in XBMC. It's only in their development branch (Frodo), so everybody running it is running experimental code. Of course, DTS and AC3 are supported, both bitstreaming and decoding, downmixing and so on. It's only missing Dolby True HD and DTS-MA. Since I watch movies in Spanish, that's unimportant to me.. as usually we only get DTS and AC3 audio, the last one being the most common.
As with HD audio, I believe PVR functions are also only in the development branch, so it's not really an optimal choice to use an XBMC build with PVR functions, as it's not even alpha software.
For me, my HTPC box just plays my Bluray rips (about ~400), my tv shows and my music (mp3 and Flac) through my AVR and providing a nice interface. I realize that, some people, after spending §300 or §400 for an HTPC they want it do a lot more thing, like being an advanced file server, a ripping machine and maybe even a gaming rig. Then, of course, openelec isn't for you. However, I just wanted a popcorn hour or WD TV like device with unlimited support and that just worked... and for that, my ION with openelec is just perfect.
For those who still are looking for an appliance feel but want some more advanced features or more control over the machine, there's also XBMCbuntu, where you have a full ubuntu system under the hood, but where the conventional desktop has been removed altogether and replaced with XBMC.