I've installed WM5, and so far I like it. Most of my apps port just fine to the new OS, and a couple others I just have to wait for new versions (in development w/ manufacturer).

So far, there's nothing that causes any usability problems with the new OS. I've got an Axim x50v. However, a couple of odd things.

1. ActiveSync seems to launch itself repeatedly. By itself. Little gremlin When I'm done using the Axim, I'll use switcher bar to close running apps, then turn it off. Next time I turn on my Axim, ActiveSync is running. I'll turn it off, and a few minutes later it's running again. Odd. Not any hinderence with usability, but just strikes me as unusual.

2. Sometimes the device will lag for a few seconds. I can click something, and it takes about 1 to 2 seconds to activate. The Axim will stay in this state for maybe an hour or two. Then sometimes, the same processes will activate instantly. I set my processor to a single speed to see if the auto-adjustment were causing the lag, but it did the same thing regardless. Again, it doesn't hinder my usability of my PDA, just kinda odd.

Overall, I think I like WM5, though.