Well the change has been announced multiple times some time ago, so it’s definitely not a surprise 
This new layout will take a bit of time to get used to, but it works really well, is technically up to date, you can use it on a mobile, you’ll be able to reply by email, the search is really awesome, it looks a lot more fine tuned and there’s all kinds of little other new things to discover. So… take a look around, please do ask where you encounter problems. And have an open mind 