simply put kontakt is the best vsti sampler ever: the interface is easy and fast, the sounds is very good and the features are too much..!!
BUT...i think NI was too much in hurry to release it and the 1.01 version has lots of bugs and is quite unstable..
buglist
the 2 biggest bugs: 1) cannot read ANY akai sample cds, they are aware of it and they say that "with some" but i tried with dozens of cds without success and i don't know anybody who was able to read an akai cd with kontakt (please if you can do it, reply to this post)
this is weird because , as much as i know, battery do this job quite well so NI have the technology for this task...
2)when the output for the sampler module are set to "groups" the FX do not work...

3)when a sample module is in "time machine" mode sometimes the speed knob doesn't work ...unfortunately i don't how to make this problem appear and disappear..(sometimes even closing cuibase and reopening and still the the speed knob doesn't work..)

4)if you create a new folder while kontakt is on the new folder is not "seen" by the browser..you ahve to close the host application and reopen

5)the "edit all" button in the group editor, when is UNSELECTED (light off) sometimes doesn't work properly, the edits are applied to all the groups as if the button was "ON", also trying and trying at the end it works properly..but it is quite ennoying...

6)If the feedback of the delay FX is set very high cubase become very unstable when stopped and crash very frequently unless of course is set to "enable audio only during play" (this could maybe be a problem of cubase...)

well this is just my personal list, but i hear that people have found many other small bugs so come on post it...
also it is of course possible that i am a bit stupid and i thought was a bug something that i couldn' understand...