I haven't had any trouble with the firmware betas. Usually if there are little hiccups it's on some new feature that needs a little fine tuning. I'm currently running 2 betas behind right now, only because I've been really busy (building a new house) and really they do most everything I want already.
As for how it interfaces, it basically hunts down Windows shares (or Samba shares if your a Unix guy) that are named certain things like "Music", "My Music", "Audio",etc. It can also be configured to just use other share names, servers, etc by hand if you want through the Web interface. For example I can stream things from my work machine on them at home.
For streaming stations they have a Web site you use that allows you to set up and manage your streaming channels. Then the Audiotron just contacts it to get your channel lists. If you have a decent connection, streaming works great.
One thing I should mention is that I do use all them on a connected ethernet network (100mbs switched, but that doesn't really matter as 10mbps is fine). Some people using the HPNA connections randomly post probs to the list. However, I *really* think most of that is just inherent in HPNA with borderline conditions. They are working on better drivers though. Really everyone should be using ethernet IMHO. Some are even using the wireless ethernet 802.11b stuff now that it's very cheap from people like Linksys.
As far as control, you'll get a remote control that will give you pretty decent control. However it also has a Web interface that will give you far greater control and more features to play with. There is even a "tiny" version of the Web interface that you can use with things like wireless Pocket PC's, Palms, etc. Makes for very slick control as you browse your entire collection on a nice Pocket PC screen and have full control.
In any event the product has grown into a pretty mature piece. Once you dig into their web interface a bit I think you'll be impressed.