I'm pumped that I recently switched from Tiles to SiteMesh in AppFuse. Not only was it easy to learn when I integrated it into Equinox, but it easy to replace Tiles with SiteMesh in AppFuse.
The best part of SiteMesh is once you have it setup and configured, you rarely have to muck with it again - it just works. In fact, it's so non-obtrusive that when I re-worked all AppFuse's tutorials last week, I was able to delete a whole tutorial. That's right folks, by removing Tiles and going with SiteMesh - the number of tutorials dropped from 5 to 4. Reduction in code and words needed to explain it is always a good thing.
Furthermore, SiteMesh continues to be evolving and getting better. Good stuff.
BTW, did you know you can use SiteMesh-style templates in your Roller blog? I'm using this feature on JRoller and it works great.