It has been used in our project for several years now, so we have gotten to know it well over time! As I am not involved with IT anymore myself (I've moved into marketing), this doesn't really bother me too much as long as they keep up their support of contaothemes/themes etc., which seems like will be happening anyway due to its popularity among CMS users worldwide - at least that's what my experience tells me :-) The only issue about CT itself was finding out how easy or difficult certain things were if you are new / unfamiliar wih them.
In general though there isn´t anything bad enough here either :). There should always just come something "wrong" somewhere once in awhile when working around these systems but nothing major ever comes along unfortunately ;-) We use CPTs mostly because it makes SEO easier than using custom fields since all data gets saved under one single.