Interesting - Makes you appreciate the final version
Most of the music is preliminary or alternate versions of the product which was released to the public. Even though the final version is much better most of the time, it's very interesting to observe the evolution of a song. One in particular is "One After 909." The early version almost hurts your ears, but the final version on Let It Be is one of my favorites of all time.
It's also interesting to listen to the early tracks in which Pete Best plays. I can now see why his contributions helped drive the music during live shows with his boom-boom bass drum, but doesn't really work on the recorded product. It's hard to deny that Pete got a rotten deal, but Ringo's style was clearly the better fit.