Look how quickly mine went down this morning - I took if off charge, turned the screen off, and, within about two hours, media server took up 70% of battery drainage and drained my phone from 100% battery to 60%. I then updated my OS to 4.2.2 and the unnecessary battery drainage has reduced greatly.
The media server percentage is now going down as the proportions even out. I hope it's better now. You can see exactly where I updated the OS, although I did play some games before taking the screenshots, so the dip at the end of the graph is expected.
I didn't have a problem with my battery life until this morning. My phone has always lasted me all day, which is all I need.