I tried to make clean install, to be sure that this v4 is working stable, but it doesn't. Avoid it like a plague. V3 is cool enough. No issues whatsoever. V4 is like messed beta version. Bug here, bug there.
That's strange, a lot of users are reporting that, but it's relatively fine for me.
I had programs crash on me only once, and when I rebooted, everything was fine.
The only thing that bothers me is battery issue, sometimes Android System is the highest power user, something is keeping the device awake (but doesn't happen always).