For all my reading about them a couple months back, I just got my first one to work. Set it all up on Slackware and went through the usual problems/issues of learning the Tomcat setup with Linux. Spent a large block of time and never lost any motivation, got stressed or tired. That like never happens. 
Got a JSP to work now; nice to know that it all works. I’ve been going through the Head-First book on servlets&JSP.
My goal is to create a working web-app for a portfolio that I can use to display my abilities. First part I did was to create a DB schema for a hypothetical plant that assembles PCs, and that took quite a while to get straight as I was used to sql, but not designing databases.
Sounds great
Well I hope you will get done that application and post about that experience too.