Electronic Simmons SD1 practice pad - any thoughts?

Looking through my recent GC mailer I see the following Simmons SD1 electronic drum pad. This would seem to be the kind of thing I would like working with:
  • Substitute it for precise hi-hat tempo
  • Measures of mixed 8th, triplet, 16th, 24th, 32nd
  • Practicing polyrhythms
  • Properly timed back-beats
The description mentions it can also be used as an all-around tool for providing percussion sounds not in your kit. But they don't mention what kind of speaker(s) needed to back this up.

Can anyone provide some first-hand experience for this device?
Does it fall more in the "knock your socks off" or the "just another gimmick" category?
If I decide to buy it - do you want to know anything in particular about it?

Drum on!