Linear levels are great for starters, and can be a good refresher once you've gotten into making non-linear levels. However, it is somewhat difficult to make stand-out levels with a linear structure. That being said, it is not impossible. And as said before, it is also subjective and ranges from person to person as to which they like better. I personally, like getting from point A to point B, rather than searching for alternative paths or solving large puzzles. (Which is because I'm lazy, of course
I would like to ask, what levels have you seen gain low scores due to being linear?