I just "upgraded" to Painter 13, and it sucks. Sure, the interface is nicer than the previous version, by some minor factors, BUT...
It's slower than molasses. Even after tuning it to be faster. I suppose that may be some small part better than version 12, which just fails to work at all in OSX Mavericks unless you go in and screw around with its guts, and then some things still cause it to vomit itself to death.
I do like how FINALLY, after 13 versions, you can actually import brushes from another person, or an older copy of Painter. Which they have been lying about in the manuals since version 6.
But then you still can't use it for the slowness. They claim it is faster, but it is not.
So in frustration, I went back to version 11, and it is screaming fast. So screaming fast, in fact, that I believe that it actually improved my art, since I was able to do stuff that would have frustrated me from waiting too long to get it done. So I am just going to use version 11 from now on.
Massive failure, Corel.