I'd put this movie on the same list as things like, Smoking Aces or Shoot em Up. The effects really aren't too bad, some pretty decent gore effects and more than copious amounts of blood, but all the gun play was surprisingly well done. Throw in a few unexpectedly touching moments, some rather clever lines, and you have a rather enjoyable movie. As long as you don't expect any kind of real plot at least. The most impressive thing about the movie is that 95% of it is all done in the same room, and not many movies can pull that off without having it get boring, but this one did.
As I said in the summary, it's a brainless bloodbath with a strong, sexy female lead. If you don't mind the gore and you just want something to watch, this one isn't a total waste of time.