I've been quite happy with my IPS panels, IPS224V (x3), 25UM65-P (x2), B276HK, 25UM55 (x2), and now a U3415W. I can't remember what monitors I had beforehand, but they were not IPS. I remember being amazed by IPS' colours and I have stayed with it ever since.
The U3415W has been the only one...