Why wait to whine, when you can do it right now! You are right though, some people will find reason to complain. But do understand, that they frequently have legitimate reasons in their mind. That's true even if others don't see things in the same light. For example, I don't have huge issues with the "Modern" UI in Windows 8.x. I don't like it, but it certainly does not make or break the OS in my humble opinion. Likewise for the excessively flat appearance of Windows 10. Once I poke out both of my eyes on the sharp edges that appear throughout Windows 10, I didn't understand what all of the fuss was about. Yet even though I find those things trivial, other people obviously do. Just look at the adoption rate of Windows 8.x and how Microsoft is partially back-pedalling in order to satisfy their customers.

That being said, there is also something to be said for waiting a few months to see how it is received and to let other people work out the bugs. If you don't subscribe to that approach, fine. I know that I don't because I love playing with new technology. Yet for the vast majority of people, they would rather stay with the tried and true until they decide to move on There is nothing wrong with that.