I have an older Roku with an unofficial YouTube client on it. It's not heavy on features but it allows searching and is fast and simple, and has no ads (that is probably why Google is changing things!)
I have a Roku 3 and the YouTube client on there is awful, it's slow and cumbersome and worst of all it keeps autoplaying videos after the one you're watching finishes, with absolutely no way to turn that off. No doubt it is to display more ads for those that accidentally leave YouTube running, but if I was an advertiser that little trick wouldn't make me happy.
For now I'm sticking with my old Roku, but I know the days are numbered.