I too have noticed weirdness with changing themes and the latest firmware. I'm not doing anything special -- just trying out the built-in themes and wallpapers. They seem to take a long time to load and the themes don't seem to "stick" properly.

Links and virtual keyboard weirdness in Opera are confirmed here, also.

My WiFi is much improved, though. I couldn't access my work network at all before; it works like a charm now.

I haven't seen a memory warning since flashing, either. (But, admittedly, I had so many problems getting both the WiFi and Opera to work properly before my latest update that I had gotten out of the habit of using the 770 to access the Internet. It's mostly an e-book machine for me.)