If you remember one of my previous rants, I mentioned that there weren't many IDEs other than MS Visual Studio that had good GUI builders associated with them. One possibly strong alternative I ran across was Allegro Common Lisp.
I downloaded the latest free version from Franz's website and installed it, along with the license key. No problems there. I started with the interface builder tutorial and began working my way through the chapters.
I encountered a couple of main problems. One is that the IDE is just buggy and doesn't always save your changes correctly. This is flat-out annoying for a 6.2 release. The second is that when adding a new class to the your source code, you have to manually "evaluate" the class in order for the IDE to recognize it in its internal GUI Designer. Come on! Visual Studio and Eclipse have done dynamic code parsing for quite a while now.
Frustrated, I gave up on the tutorial around chapter 4 because I just got tired of fighting with the IDE. Scratch ACL as a good alternative language / GUI building combo.
Right now, I'm back to VisualWx, which I'm pretty happy with at the moment, but I haven't stressed it yet either.