Certain aspects are obviously disappointing to me, but as a whole, no. I love the game, and think it’s the best in the series so far, and also contains three of my absolute all time favorite missions (masterpieces in design) in the series.
Like others have said, stuff like the missing Briefcase could be aspects that are disappointing.
Escalations are quite hit-and-miss in my experience, with a lot of it being based on how the Escalation is designed (some of them I have thoroughly enjoyed, others have been a chore)
I also feel like two of the levels are of noticably lower quality in terms of design / design choices.