I used kdevelop 2 long time before version 3 exist. Version 2 is not so intuitive but it works. Especialy version 2.1.5 is very stable. Now I use kdevelop 3 and I must say it is not so stable. It crashes during documentation brwosing and some other things. I dislike the IDEA mode because it is pedantically in my daily work. But the tabbed mode fit my needs.
I have problems with the make-tools editor. How I can add a existing file and then define a target where the file should copied during a "make install"? I kdevelop 2 was it quite easy but in kdevelop 3 I don't see any easy way to do this.

other thing are the file groups. I spilt my projects into "heade, source, gnu, icons, ...". It is possible to change the predefined groups, but you have to do this for each project. It is not possible to change the given groups permanently. This is a little bit anoying.

But kdevelop 3 goes the right way but it is far away from a stable and usefull version for all the user needs. (But it can fit to all needs of some users, but not for all!)

The documentation browsing crash is well known and very frustrating. http://bugs.kde.org/show_bug.cgi?id=76558
One workaround is to set the project's documentation settings to show _all_ installed documentation sets. The doctree does some odd things to hide documentation sets that makes the Qt style plugin crash.
The bug is IMHO in the style code, but the documentation plugin is currently being rewritten, so the next release should have a better documentation system and not have this problem.

The File Groups comment is a good point. You should register a wish report about that so it's not forgotten. http://bugs.kde.org/

I used KDevelop 2.1 for about 3 months before switching to KDevelop 3 and it is a HUGE improvement. The auto-conf manager takes some getting used to, but once you do it is much more flexible and powerful. I absolutely love it! Before 3, I would do most of my development in VC7 and then port to linux. Now I'm doing it the other way around. Kudos to the team!

Decoding, I'm not sure what you were looking at but I've got to assume you 1) either didn't spend much time with it, or 2) you had something wrong with your installation. When I installed initially, I wasn't setting my --prefix correctly for KDE so I wasn't getting any toolbars or icons (which basically made KDevelop look like a bad text editor).

My only complaint, and this is probably a misunderstanding on my part, is that I have been unable to create subfolders within my projects without compiling them as libraries. Anyone know if this is by design?

I personnally think that Kdevelop 3 is easily the best Linux IDE I've ever worked under. I used to dislike kdevelop2, but version 3 blew me away. It is simple & powerful at the same time. I especially like the new IDEA mode, which lets you see your code fullscreen. Doxygen integration is great, and since the IDE, it is plugin oriented, it gives room for extension... thanks to the developpers.

i don't use an IDE personally, but i've heard nothing but good things about KDevelop3. what in particular about KDevelop3 did you find so inferior to 2.1?