Be really careful with this, I had a hard freeze, finder lockup in deleting 1,800 photos out of a folder on one my drives on my brand new Mac Pro and it toasted the drive.
I went back to OSX 10.6.8 permanently as this is by far the nastiest OS version on launch I have seen in over 20 years...
I am skipping this OS entirely, will probably go for 10.8 when upgrading hardware in 3-5 years, this one is total BS for pro use....