Roger Ebert's review was perfect. Go read it.

Rating: 6/10 (26 September 2018)

I had to check this film out after I was vastly let down by BlackkKlansman since this was on Netflix.
And after a dull start, where the movie seems to introduce way too many side characters, the movie gets going. The point of the film, the bank robbery, is presented very well. I enjoyed all the bits inside the bank, and the interactions with the characters seemed very natural and it was a thrill to follow.
Even though the police central command seems to be some kind of tourist attraction with free entry to anyone.
And even though the police raiding the bank seem to have no idea how to raid a building after it's been taken over by armed criminals who have disabled the cameras, wired the ransom note with listening devices. The cops just go in there switching lights on and just seemingly irregularly proceed through the bank.
And eeeven though all the stuff the robbers hand out, are just casually taken into the command central. Thank god they drove the robbers' truck away, I was expecting them to just casually open the truck doors. This movie has a lot of illogical stuff going on.
So then we get to the point in the movie where the bank robbery is over. The payoff is finally revealed, and the rest of the movie happens. I realized that I had literally zero interest in Christopher Plummer or Jodie Foster stuff going on, anything answering the WHY did they rob the bank.
Inside Man takes its bloody time to get to the end where everything is revealed, and all the secrets revealed are just dull. All the actors do a very solid work with the film, don't get me wrong. Everyone is very natural and charming in their own way in the movie. Especially masked Clive Owen, he was great.
It was still an ok movie, even though the beginning and the end are significantly weaker when compared to the middle section. Especially the end. Propably never going to watch this again, it was too long to be casually enjoyed.
I would still recommend to watch it, I enjoyed the scenes inside the bank. 6/10