I use Clack for all web-development in lisp now. With Caveman2 you will have a pleasant lisp web experience :)
As the web documentation states:
The reason why Clack had only a few bugs so far is plenty of quality unit tests. There are 173 tests currently. The test coverage has been kept over 70% since its first official release.
All releases have passed the test suite on three CL implementations: Clozure CL, SBCL, and CLISP. You can check the current status at http://ci.clacklisp.org/.