And in case you didn't catch it on that page, an interactive demo:

http://www.rolandus.com/PRODUCTS/demos/hpd15/demo.html

I like the "Sitar" one because one of the pads is a toggle trigger, so you can do a continuous background chord with it... [edit: must have been a glitch in the demo software, can't do it any more.]

That's something you can do with the V-drum sound module, is create little melodies or chords with the pads. For instance, you can program a pad to play a different note in a melody each time you hit it. So you just hit the same pad ten times to play a ten-note melody, for example. Can be backing chords, too, so you can keep a chord progression going while still doing the rhythm. Quite interesting when you see someone talented doing it.