Better than some reviews make it sound like

Rating: 8/10 (1 October 2019)

First of all, lets address the "based on true events" that some people complain about. It's based on real events but being a film it's dramatised with added bits/people that didn't really happen, it's not a documentary. If you want a 100% accurate account, a film is probably not the best place to go.
On that understanding, if you have a little empathy you still get a clear idea of the terror the real guests and staff would have felt, the bravery of the staff who chose to stay to help their guests and the brutality of the terrorists.
It is a 2hrs film and most of it covers the attack on the hotel so for some it may seem long but in reality it was a very long attack so they had to represent that. I personnaly felt there was plenty enough tension not to feel the time go by and enjoy (if we can use that word) the film.
Jason Isaacs playing a Russian was odd and the couple (Boniadi and Hammer) and their nanny were cliche, hard to believe in and ultimately you may struggle to care for them.
For me Dev Patel is the clear star of the film and although his character is semi fictional (based on 2 different real people), he feels real and very well acted.