It's not as simple and straight forward as Yamaha's system, to put it simply...

I found the menu system very UNintuitive. with the global settings, and the "performances" which use the same buttons as the Voice buttons, all in all I found it quite difficult compared to Yamaha's simple system, with Registration's etc...

Don't get me wrong, I still like Korg, and lots of the Korg sounds are much more realistic than Yamaha.

I also like that you can put different time signatures in one beat; that is, let's say 4/4 in variation 1, and 3/4 in variation 2 which you CANNOT do in the Yamaha.

But in general, I think Yamaha is much more straight forward. That's all.