Mavericks drops another set of iOS apps onto OS X that don't need to be there
Like what, exactly? I use Maps all the time to find lunch restaurants and search for addresses. I don't use iBooks extensively because my laptop isn't an ideal leisure reading environment, but it's certainly nice to be able to open manuals I bought on my iPad and want to read at my desk.
There's been no battery life improvement.
Speak for yourself. If nothing else changed at all, I love the "Apps Using Significant Energy" menu item on the battery icon. It's nice to know that some random unexpected app is gnawing on my battery so I can ask their support to please fix it. Judging by the number of app updates I've gotten that contained nothing but power fixes, I'd say it's working.
I'm not going to claim that Mavericks is the perfect OS or that everyone should love it, but it certainly has a lot to commend it.