I have been using the Logic Tech wireless keyboard and mouse for about three years. Battery life has never been a major issue, however it can be very deadly if they run low while you are in the middle of an online game!
The funniest thing was when I first set it up and my sister-n-law wanted to use my computer. She sat down and of course immediately had a problem and called me. Rushing over, with an expression of horror I asked her what she had done to my mouse?
She hasn't asked me to use my computer in awhile now!