In my opinion, Glassfish still has a lot more to spend on ease-of-use (this includes documentation) and footprint/startup time. Tomcat is way ahead on both counts. I prefer Glassfish' community but it needs to pick up on the two points I brought up.
Most of all I would recommend they focus on ease-of-use. The documentation looks like it was written by IBM. It is a huge tangled mess. It should be more obvious how to do things without referring to the documentation as well.
[Message sent by forum member 'cowwoc' (cowwoc)]
http://forums.java.net/jive/thread.jspa?messageID=324186