There's no problem with the cast but what I found rather off-putting was the fact that MARVEL lost its creativity. For the past 2 decades marvel has been on top simply because of the great stories it came up with; Thor and Loki, Age of Ultron, The Avengers etc.
The Thunderbolts idea was very great. It could have been a different band of heroes just like the Guardians of the Galaxy or Fantastic four or something. Instead they were made to replace The Avengers. What a silly mistake by MARVEL.
It seems they lost that edge. The whole movie was like a therapy session... With Yelena crying and sobbing and Bob talking all about his past. At the end we couldn't even identify the Antagonist in the movie.
This is not how I knew Marvel. I started seeing mistakes like this when the new captain America movie came out earlier this year. MARVEL could do better than this. Besides during the cast session I saw one writing by the editors that said "Heroes nobody asked for" and it was true. MARVEL has lost its great stories and writing. In my opinion this wasn't MARVEL at it's best.