After the initial slow start (see below) my machine is now up and running with OS X Yosemite and it looks really nice. No more slow response when switching programs and scrolling.
It does seem that my battery life has improved in OS X Yosemite. I’ve been using my computer for many hours and it’s still over 50% of battery left. I’ve done mostly light editing in Adobe Lightroom and web surfing and occasionally trying out the new functions in OS X. So far it’s looking good. A lot of friends doesn’t like the new look of Yosemite, but I love the new design.