Just barely finished installing it, so I can't comment on battery life, but I hope that it improves battery for me. Any extra battery I can get is great!
I never noticed safari being at the top of my usage list under battery usage until after the 8.1.3 update. My habits haven't changed but I feel like safari is taking more battery than it used to. Just my 2 cents in the last couple days evaluating 8.1.3