I will be honest, I am maxed out completely at the moment and haven't had much of a chance to look at the new IDE from QT Software. I have however, been reading some interesting posts from around the KDE community which seem to be split as to whether or not the application is a good move and welcome.
The KDevelop team seem to think it is a duplication of effort and I can see why. However, as someone that spends much of his days battling, erm I mean enjoying(!) Visual Studio it always suprised me that QT did not have a good IDE of it's own. I have loaded monkey studio and tried to build something with code blocks. They are both ok IDE's but VS does provide a benchmark for IDE functionality. i would say that VS goes so far as to make certain tasks very easy and some programmers very lazy. I don't think that this is a good thing but that is my opinion.
I have used KDevelop in the past but have not always found it's UI to be particularly easy to work with. Of late I have started to head down the same route as Aaron and Ivan, basically Vim is my friend. Both of those previous links are to posts relating to QT Creator and KDevelop. Aarons makes for very interesting reading while Ivan basically agrees.
As for me well I installed the windows binary of QT Creator this morning while waiting for a build, fired it up and got a memory error. Tried again and it fired up. First impresssion is that it looks professional. Once I have tried to use it I will report my honest opinion.