My friend and I pooled our money and shelled out $500 for it. And let me tell you... Maybe it's just me but this thing is nuts! I'm having a blast. We're gonna use it to write a peice for the school band, but right now I'm having a blast. Rather than sitting around hitting random notes and chords for inpiration, I can do a little clicking around and hear how it would sound instantly. The vocal playback is a bit to be desired, but everything else sounds really cool. I'm not sure if it was worth $500, but I just got it and haven't had a chance to see all it's features.
I'm sure it's quite the program, but I've used the demos...frankly, even with all the awesome features that wouldn't be available in the demo, I can not imagine it being worthwhile enough for $500 USD.