I think its now more than 4 years in my quest for a decent media center software on my Mac Mini. I tried a lot and so far I always turned back to Frontrow. For Boxee however I will leave it at least installed on the Mac though it cannot replace Frontrow to full extend:

- as many of these media center solutions it is labeled "alpha" and it will probably stay that for ever...

- it comes with yet-another micro-social-network share idea which forces you to "subscribe". However its easy and you can disable most of it.

At first test it was surprisingly stable and had nice feature like labeling all my local TV-series episode automatically. But after some months use crashes are becoming more frequent.

Boxee like other programs promise you easy access to online media, video sites, RSS feeds etc. Its doing fine with popular feeds like Revision3 but fails most of the for user selected feeds. This is not really a surprise as most RSS subscription to video feeds do *not* work with external software but are designed to be displayed in Web-Browsers.
Also the promising build-in Torrent client did not work for me at all. Providing Torrent RSS feeds picked the right files but never managed to download anything.

So for the moment I keep it on the Mac and hope for an update (last version already 5 months old).