The new interface is a little bit of a culture shock at first, but you soon get used to it.
I can highly recommend learning to use the voice commands, as you rarely need the menus then! To get to a specific channel, you can just hold the button and say channel names, like "BBC One" or "Sky Mix HD", etc. Other useful ones to start with are "My Recordings" to go straight to the recordings list, "Skip forward x second/minutes" (e.g. "Skip forward 3 minutes" or "Skip back 30 seconds") instead of pressing the forward/back buttons multiple times to do things like skipping adverts.
If you want to go straight to an app, like Prime Video or YouTube, just hold the button and say the name of the app.
There are things I miss from the V6, and some new annoyances (like getting an advert when I switch it on!) but its not quite as bad as some people say.