I'm not a keyboardist, but bought this for my daughter.  I have played around with it quite a bit and find the sound amazing.  It's most obvious flaw (small keys with only three octaves) can easily be solved.  We have a cheap, old Casio with full size keys and six octaves.  I just ran a MIDI cable out from the Casio into the Microkorg and, voila, you can play the Casio and hear the Microkorg.  Of course, I also had to buy a dual mount stand (which looks really cool), but it improved the usefulness of the Microkorg threefold.  Also, each voice on the Casio creates a new sounds with each voice on the Microkorg.  If you have the Casio volume down all the way, you can't hear its output; or, you can run a cable into the amp and hear both the actual sound of the Casio voice PLUS the Casio/Microkorg voice PLUS the Microkorg voice by itself (if you reach up and hit those keys).  Needless to say, this creates millions(?) of possible sounds.  So, get the Microkorg, get a dual mount keyboard stand, and buy some cheap old keyboard off of Craigslist, and you're set.