Mavericks works better than Mountain Lion, though. My MBA from 2012 is working better than it ever did before. I'm even using the beta of Yosemite. But Mavericks was definitely a step up from ML, which was a step up from Lion. Better battery life, better performance, when comparing Mavericks to ML.
I tried it on both my Macs, and it was a disaster. Same for all my family members and friends. The common factor was that we all had HDDs, not SSDs. I think Mavericks accesses the hard drive a lot more than it should, and that's not noticeable on new Macs with SSDs.