I have installed Bad Behavior 2.0 Alpha 3 on my site. Akismet has been very effective (maybe 1 or 2 spam are missed per 300-400 comment spam with no false positives), but I had to go through the 400+ comment spam it catches every 2-3 days and I would love if the obvious stuff is just blocked before it reaches Akismet. The less work I have to do with comment spam, the better.
So Bad Behavior will be combined with Akismet to effectively shut any chance of a comment spammer getting a comment posted on this site. If Bad Behavior misses it, Akismet should catch it. Already this morning, 47 spam attempts were blocked by Bad Behavior. Fantastic!