Lots of bugs and complaints about bugs. They removed it from the version 5 collection (I got it with version 4 I think), perhaps because of the bugs? I already had the Dubstep version due to some crazy discount deal at JRR one xmas. The stand alone versions sound library's work with Spark 2 also.
It is kind of neat (and fun), especially some of the patterns and kits and the way it was meant to be played (I guess with their hardware). It really needs an update though. It does have some very nice sequencing tricks and the kits are actually decent. But at this point I'd be worried it's more abandonedware. I do believe they will someday update it, but that may be so far out you'd be better off not counting on it.
If you could get it at a big discount I think it's worth having, especially for dance/EDM/Hip Hop.