NG2 will be a great game, but MGS4 will be better. I say that having loved the first Ninja Gaiden on Xbox to death. Other reviewers have said cutscenes haven't been that bad or intrusive in length, but to each his own. Unlike some people on this website, I don't base my enjoyment of a game off its reviews.
Is 90 minutes intrusive?
no comparison really
Sure, you can compare games to non-games. Hell, they compare Wii Fit to other games. Ninja Gaiden 2 being the game and MGS4 being the interactive movie instead of a game.