Ever since my Motorola Razr got updated to Jelly Bean about 3-4 weeks ago, when I charge via USB, the topwards center of the phone gets extremely hot. Even though it says its charging, it's actually eating the battery. I do have the HD dock for when I go to bed and so far, this has been doing just fine. This didnt occur when I had ICS.
Also, every so often, when I turn on from sleep to do something, it seems supper slow like something is going on in the background and the multitasking would be nonexistent. I believe the JB update missed something with the multicore usage, because there was never this issue on ICS.