Does anybody have experience of a decent J2SE (preferably at least Java JDK 1.5-level) Java Virtual Machine for Windows Mobile 6? If you know of any CLDC VMs, I'm also interested because even that would be better than what we currently have for the platform.
Yes, I've tried doing things with Java on Windows Mobile. I tried really hard. The best advise I can give you is: Stop right now, and start using .NET Compact Framework.
Anyway, the two 'good' JVMs for WM are IBM-J9 and NSICom Creme, which still are both terribile to work with. You've already seen Creme - IBM-J9 isn't much better. They are slow, clumsy, not native looking and hard to install for end users. Also don't ever think of doing exotic things like dialing a phonenumber or even launching another application. If you really want to try, there's an evaluation version of J9 available here. (which is identical to the full version).
I'm not against Java in any way, but on Windows Mobile i recommend saving the trouble and using C#.