They have a few quirks but nothing that isn't fixable. The motor (like all Kawies) can be an absolute screamer with some cams, piston, etc.

 

The kawi 450 frames have a habit of cracking when I work at the motosport shop we have 9 or 10 of them come in for warranty because of it and we found out later on it was from people jumping them and frame couldn't handle it