This is a spoiler free review.
I love the MCU and I have been a big fan of this franchise for many years. I gotta say this one is on the bottom end of the spectrum. I do believe, however, that Marvel will learn from the mistakes they made in this film.
The main critiques I hear from others and I feel myself all stem from plot holes. Let's get this straight- the visual FX are brilliant as always, as are the action sequences, choreography, stunts, and the acting by the actors themselves. Benedict Cumberbatch did very well in this movie, as did the rest of the supporting cast.
For me, the driving desire to watch these films has always been the characters, and I felt that the main antagonist of this film was done poorly. I also feel that a sizable portion if this movie's runtime was spent on plot points that turned out to be irrelevant later in the film. For this reason I will look back on a select few scenes and think "why are we doing this? It's wasted screen time!" When I watch this in later viewings.
Go into this film expecting a marvel film more like Thor: The Dark World than Avengers: Endgame.