I have been asked this question many a time and my reply has always been...
Jack Reacher in the books is described as being 6 feet 5 inches (1.96 m) tall, weighing 210–250 pounds (95–113 kg) and having a 50-inch (130 cm) chest.
Tom Cruise is... Height 1.70 m, Weight 77 kg, no way in a million years could Cruise be Reacher, when I saw the first movie 'One Shot' where Reacher was offered out in a car park for a fight, In the book some of the 5 guys were over 6ft tall yet there is Cruise fighting them at 5ft odd, I just pissed myself laughing, someone like Liam Neeson would have been a far better Reacher, my son though has watched both films and although he agrees with me that Cruise is not the type for a Reacher character but said he acted the part quite well, look at the Video of the fight below, Cruise at 5ft odd fighting 6ft odd guys.