For the true accounts of exactly what happened at Hotel Mumbai (and around the city) during the terrorist attacks, watch any one of the many documentaries available. This is just a fantasy version trying to mix "Die Hard" with "hotel Rwanda". It's bad. Of course, because it was marketed to American audiences they had to have an American protagonist who has to show an act of bravery...but not enough to actually result in anything, since that would prompt people to look him up and realize there were no Americans killed during the Hotel siege. And there has to be a "western" muslim to balance out the terrorists to show "see? They're not ALL like that!" And while this character was portrayed as a hot, rich Persian chick, the reality is she was a dumpy, old turk (and her husband); both atheists/secular who quickly pretended to be muslim (the woman put her sash around her head) to show the terrorists "look! don't kill us! We're one of you!!!!" and subsequently lived.
Yes, gang, the reality is far more horrible and there really were very few heroes or likeable characters at all...save the waiter and head chef portrayed who really did help many to safety. If you have nothing else to do (i.e. are on an airplane) then fine, watch it (that's how I saw it). But don't expect much.