3. Power management?
So this one is tricky. As I said, I am using a 2009 MBP to judge the power management, so the battery life isn't going to be as great as a new MBP. However, I think its safe to say that the battery performance should not be worse than before. Although my battery is 4.5 years old, it still contains around 75% capacity through deliberate care and maintenance on my part. I have maintained and cycled the battery pretty well to maximise its life.
Although, I'm not too fond of Mavericks, I find that my battery life came with a positive outcome. Although i do have a 2012 Macbook pro, i roughly had an hour increase in battery life. Went from about 7 hours of wifi usage and normal tasks like microsoft word, web browsing, email, iPhoto, iMessage, iTunes and half screen brightness to about 8 with Mavericks. I know I'm not the most demanding user when it comes to my Macbook pro (i leave most of that to my custom Windows machine), but to most of the average users out there, I'm sure that mavericks provided a decent upgrade.
I will say that i did a fresh install after backing up all my files, so i'm not sure if that would fix the issues you are having.
As for programs loading slowing, my experiences are still the same. They start up with one click and one bounce. My MBP boots up in about the same time as mountain lion did, but now it boots down much much faster with Mavericks.
The wallpaper issue you are having, that i honestly don't know. Maybe yo could double check you wallpaper/screen saver settings to make sure it isn't checked to change every few hours (or days).
If you are willing to back up your files, and are patient, try to do a fresh install and hopefully things will clear up.
