I totally agree. I reverted to the last version within 20 minutes. Apple has flattened and oversimplified its latest OS X, but the herd does not need to follow a single cow. I know some Mac users who dislike the new flat look. I agree that there should be an option to revert to the old look.
I know the appearance should not be an issue, but I find the flat interface too--well, bland. So bland I uninstalled ver.5 and reinstalled the 4.xx version I had. Even some Mac users I know hate the flat, oversimplified GUI of the new OS X. Why go that route? Perhaps you could provide an option to switch back to the old look?