Looking at the other reviews on Amazon, it seems that there are two distinct camps: delighted Windows users, and unhappy Mac users.
Sadly, I'm in the latter group. The Mac driver software (which is not included with the mic, but is a free download at Samson's website) simply won't work on my G4 running OS X 10.2.8. The control slider appears for a second, then vanishes - leaving behind an error message.
The microphone itself seems to be good quality for the money - sensitive, clean, and quiet. However, when using the mic with Garageband, there is an annoying latency problem which Samson says is unavoidable - but seems to be worse than other USB mic combinations I've tried.
If Samson retools their Mac driver to get the bugs out, then this could be a heckuva package. Until then, I can't recommend this mic for Mac users (and am still debating whether I'll keep mine or not).
UPDATED: I updated to OS X 10.3.9 and found that the Samson driver worked much better (though their materials didn't indicate that this version of the OS was needed). As such, I'm adding another star to my review (I'm not sure it'll show up - but I now give it "3 stars" - a satisfactory rating for the price)