Yes, select people are having that experience and many others are not.
I am sorry for those having difficulty, but actually, it is working just fine for many people. There's nothing "select" about it.
Me, I didn't mess with downloading until after I got the Apple email this afternoon, which had a direct link.
I put 10.10 on a separate partition and it's doing well. Nearly everything I've run into has been due to third parties not being updated (SMC Fan Control, Adobe Flash, TRIM Enabler, various Safari extensions...)
In a word, it is gorgeous. I agree that Mavericks looks like a dated and vintage OS in comparison.