Updating ios 5.0.1 has brought no changes in battery drainage, may be slight but not something that would really mean a lot after facing battery drainage issues. But again ios 5.0.1 has brought some strange bugs that are weakening the network.
I am 3g subscriber but my phone does not let me get the speed, my calls get automatically disconnected during conversations. The network signal shows a weak status and it continuously comes in and breaks. In the mean time, I have removed the ios 5.0.1 and now am feeling relieved. I would also recommend all other to do the same.
Recently I also read a news article where apple has claimed to know about this bug and also mention two weeks of time for removing this.