I think the Yosemite boot screen is perfect. Think about it, it's simple, no screen flashes, and the progress bar is accurate, it takes into account everything from POST to EFI to OS X boot and Login screen. It's a single progress bar for the ENTIRE boot process, something that has never been done before. On Windows you get a black and white pixellated manufacturer logo, a flash on the screen, then a blinking cursor, then some white DOS text, then you may get a progress bar for your BIOS, then a Windows animation logo that just animates for an unknown amount of time, and then ANOTHER loading screen that logs you on.
On Mavericks, you had an Apple logo, then a blue screen, then a slightly different colored blue screen, then black then blue again, then you got the login screen. Now the whole thing is ONE screen, and that one screen tells you all you need to know: the progress. To me that's very Apple-like, simple, elegant and it makes sense.