I just had a crash few mins ago after I reinstalled the OS entirely last week. According to the crash log, it has something to do with the "kernel_task". That sucks!
FWIW, I've used at least 2 Macs concurrently since '09, and one since '06.
I saw that most of the time people did complain about the first releases of the OS. I didn't get most of those problem, though, until Mavericks.
You have clearly never used Cheetah.
I had the (dis)pleasure of using someone's 10.1 machine, oy wow, surprised that even got released.
As a counterpart, mavericks has been the most stable osx for myself so far. Additionally the battery life improvements gave me an extra hour on battery alone. You can pry mavericks from my cold dead hands at this point. The energy tab is also really useful at finding out what is using up battery needlessly (looking at you chrome/firefox).
I agree about the battery life improvements part as a nomadic user. However, it's totally depends on which applications you are using. For me, chrome/firefox, which eats up most of the battery, is used constantly, therefore, cannot be turned off (to save energy, because it doesn't support AppNap, I suppose). I don't see any help looking at the Energy Tab as whatever it's like, I don't have a choice there.