I had intended on checking out Astaro last summer or fall....somehow the free home demo never made it to me, I got stuck in a loop of Astaro sales people calling me....so I gave up. "I just wanted to try out the freebie home one guys...stop calling me!"
This question has surfaced over on Untangles forums a few times...here's one of the threads, sure a lot of fanboys posting in it, but there are a couple of good detailed biased threads.
http://forums.untangle.com/showthread.php?t=1495&highlight=astaro
It's an older thread, Untangle has gone through 2x version releases since then (major changes/upgrades in SPAM filter, QoS has been added, etc) but you can get a good sense of things from taking a few minutes to read it.