So far my Eris 2.1 update (Verizon) is working very well. No lockups at all yet, although I had an occasional lockup with v1.5. Also, one needs to go into the new PC Connection menu and change the setting to Disk Drive and reboot in order for the phone to be recognized as a drive by your computer. No need to mount as before.
I have noticed no lack of performance, and the phone is now much faster when changing from portrait to landscape views.
The Music Player also sounds much improved over that of v1.5. I no longer hear any skipping as before. Sound quality is much more like a high-end DAP.
So far, I am very pleased with the update and the added capabilities.
Ron