Now I've played with J2MEPolish for a while, and it it has been an interesting experience. There are some very good ideas there, like using stylesheets and providing a basic GUI that actually looks nice. It is also quite simple to glue third party code into Polish code (when you finally find out where to put the libraries, see previous post about NetBans and Polish).
There are some things that are not so nice. I tried to glue the iLabs XMPP interface to Polish to produce a Jabber/Google Talk chat client. Functionally this worked like a charm, but I discovered that it is impossible to create tabbed forms dynamically. I wanted to make a new tab for each chat session I opened, but nooo, that's not possible: You have to decide in advance how many tabs your application needs, allocate them up front, and keep them for as long as you run your application. To be blunt: This sucks.