A couple weeks ago, I received an e-mail from Ray Davis of University of California, Berkeley. In the e-mail, he provided me a link to his team's Confluence Wiki - where he describes their experience and frustrations with JSF 1.1. I really like how Ray explains the problems they experienced, as well as how they fixed them. The "request thread" scope they created sounds similar to what Spring Web Flow does.
Our experience left us very happy with Spring, moderately happy with Hibernate, and not at all happy with JSF. We did manage to deliver a Pilot Gradebook that told us what we needed to know, but sacrificed reliability, consistency, and scalability to do so.
In January 2005, when we moved to full-time work on the official Sakai 2.0 Gradebook, JSF was our biggest concern.
It's a good read for those looking to jump into JSF. I think JSF 1.2 will solve a lot of problems, but who knows how long it will take to get a RI and MyFaces version of that.