No not disappointing. PR1.2 is great!
I second the findings of buxz777 and other users saying it works well.

The MicroB browser now handles certain complicated websites better without complaints and the back button greatly enhances the surfing comfort.

Flashing or not? It doesn't seem to be dangerous unless the next and final firmware will ALSO no longer flash the GSM radio correctly. It is up to you.
I remember this to be deemed a tweakers phone, and if you really are a tweaker flashing the thing to ashes in an attempt to reach the highest ... should be your greatest joy. Some of the whiners (?) are now calling people idiots for flashing their devices. They exaggerate a little and if it weren't for those daring idiots they wouldn't have any wisdom to spray around right now.