The firm is pretty good. I dunno about getting Express, the regular programs are better. I'm not too happy with the 8 second interval, that's a bit too short. I've never done zumba, but if they don't do intervals, you're not gonna lose any fat (intervals are VITAL for losing fat, since it consistently pushes your body to change, while steady cardio will improve your oxygen use, but it doesn't force your body to change)
I've actually listed a bunch of dvds that I'd recommend, you should read the question here: http://answers.yahoo.com/question/index;_ylt=AiUCDKbW66FJjmZf0Qjar.Pty6IX;_ylv=3?qid=20110519165439AAa8rA1