I installed the public beta version of Yosemite today and, stupidly, did some school boy errors:
1, installed on my only startup drive.
2, didn't check my drive for errors
3, didn't install my Mac Edt GPU
I did do a backup however, but once downloaded I tried to install and was met by a screen saying the drive had errors, luckily the install screen had the utility menus and indeed the startup drive had errors which could not be fixed.
So now I'm stuck in an install screen without many option, I was able to create a restore of my existing startup drive onto a spare HDD and then startup from the new restore HDD, lesson learned!
I then did a clean wipe of my main SSD on a PCI-e card and cloned the cloned drive onto it and used my spare HDD as the install destination of Yosemite. Needless to say that time everything work and Yosemite is running with mavericks still on my main SSD drive. Worth having the Mac Edt GPU in until everything is up and running though as certain things take time and if your like me and run mainly on a PC based card, the boot/install screen is doing things but you won't know until the osx loads.
All in all I don't mind the look of Yosemite, I'm not going to see the benefits until os 8 is released I don't think, but it's nice to run a few things and already reported a few things not working so hopefully it's helping 😱