Buy it!

I bought mine from Musician's Friend. The drum proggy is very easy to use; I'm starting to want a little more control over it, but I don't want to lose the simplicity. Not having to become a drum programmer was one of the advantages of it to me.
A downside is that you cannot import .wav's or .mp3's & record over them; you can only import .rex files. You can find .rex loops free online, but you're not able to participate in online jams & the like.*
The drum patterns are not very metal oriented; there are a couple, but most are straight rock.
The initial purchase is cheap, but you can spend tons more on it. I've probably spent 3 times the initial cost now on additional drum patterns & amp expansion packs. That's a good thing to me, though, as you can purchase additional stuff as you want to. Definitely plan on buying the Metal Shop amp pack. :headbang:
*There is an online jam community for people with RiffWorks, but it's subscription ($) based. I have not joined.