I felt that way as well to a degree, but it didn't outright bore me. I felt some of the ending missions were a lot more repetitive. Difficulty increase doesn't really change it either for better or worse. Neither does switching up the guns. I dealt with a lot worse offenders.
"I thought what I'd do was pretend I was one of those deaf-mutes.
"When you have eliminated the impossible
, whatever remains
, however improbable
, must be the truth.