compare to those commercial AVs, any good?
Well, it IS a commercial product: they're charging $49.95 per year for protection of up to 3 PCs, which does seem cheap at first glance.
However I'm not impressed by the little I've seen of MS's AV so far. I upload a lot of (potential) nasties to be scanned at VirusTotal, a site using a large number of dfferent AV engines, and MS AV's detection rate really is pretty dismal compared to most of the established products.
Personally, I'd go for either ESET's Nod32 or Kaspersky as a resident AV.
Complement that with a good firewall, SpyBot S&D's Teatimer and Ad-Aware for scanning on demand, and you'll be better off.
Just my 2 cts...
Upon checking the antivirus portion of it is now ICSA Labs Certified. The firewall didn't impress me much either because no matter what I did it had an open port that wouldn't close - maybe that was a bug they fixed.