Linear isn't a problem all the time. But games can easily be too linear for my tastes. One annoyance I have with overly linear games are when they show you this sprawling area or all these awesome details off in the background that you never get a chance to interact with because the set path of the game doesn't allow it.
It's one reason I preferred the 2013 TR reboot over any Uncharted game. While TR at its core was still mostly a linear experience, there was a lot of room to explore and move around wherever you wanted in an almost open world setting.
Ryse is a good example of a linear game done well. I mean, there's really no reason for you to move around and explore in that setting.