I've been reading since before purchasing my PE a few months ago, but this is my first post. I figured I owed it to all y'all to chime in with my Ermine results:

Positive:
No trouble downloading/installing
Have noticed speedier response/load times (as have others)
Increased app compatibility

Negative:

-Dissappointment:
As others have said, I too cannot move my apps to SD. Something I was really hoping to be able to do.

-Minor glitches:
My Angry Birds Rio menu has color-shifted very far to the blue end of the spectrum (although thet game itself remains normal)
All of my old 'calendars' are gone, and I can't add them back. Only the first default calendar is present.

-Major glitches:
After a failed attempt to use my bluetooth headset for audio (still haven't determined reason for failure . . . may be headset, may be Ermine), I cannot get any audio back out of my PE speakers. Audio still transmits through the headphone jack, but not the main speakers (except a very, very faint sound when both system and media volume are set to max), even after unpairing headset, playing with the volume settings, resetting the device, restarting it, etc., etc.