I upgraded my EE earlier today. So far, it's a worthwhile upgrade. A few app shortcuts disappeared from my home screen but otherwise it went fine. My Library was still intact, pdf's opened fine in the Reader and looked fine, email still worked, apps all worked, etc.

I downloaded several apps from the Amazon Appstore without issue and all of the apps ran perfectly. Well, the games ran but at about 1 fps I remember Robot saying that either the EE doesn't have a GPU or it wasn't enabled and it shows. A few more positives:
* Apps open faster
* Opera browser now works and I can sync my bookmarks, etc. with my laptop and desktop
* PPTP VPN now works - I never could get it to work with my router before Ermine
* Twonky has a free app so I can stream music from my DLNA server. It also turns the eDGe into a DLNA server to stream to other devices

Menu animations and scrolling seem about the same speed - still not smooth. This is probably due to lack of GPU though. I haven't tried hibernating yet.

The only issue I found had to do with color rendering, which only occurred in apps. All of the colors on the homescreen are fine. For example the red "O" in the Opera icon is the correct red color on the homescreen. However, after opening Opera the "O" on the menu bar, which is supposed to be red, is colored blue. This is also true of the web pages displayed. All the reds are blue. I also installed the game FlightControl (don't bother - it runs even slower than Angry Birds) and it also exhibits an overall blue cast. Anyone else seeing this?

After owning my EE for a year it's finally becoming the powerful tool I was hoping for with this update and the Amazon Appstore. I think the EE really was ahead of its time. It will be a shame if enTourage doesn't stick around.