Just the basic problems:
The phone takes 4:30 to boot up, (but everything works fine and fast enough after it's booted up, and that's after a lot of tweaking.)
Pathetically little storage memory for apps, and the phone makes it almost impossible to extend the memory for apps, (finally solved the problem with Link2SD, but that's after days of tweaking and fiddling.)
The phone either can't multitask or can't effectively switch between tasks. Everything I am using a web browser or following a GPS or playing a game or using another app, if a phone call comes in and the call screen pops up, everything gets messed up. i.e., the browser or game hangs up or crashes, the GPS loses its map display, the apps stops working and closes, etc. The phone just can't multitask effectively. I blame it on the single core.
... have to go. I'll add more later.