Men can do Pilates! Joseph Pilates was a MAN.
Men are built slightly different to women of course and tend to have tighter hamstrings and less flexibility in their hips, but men can also reap great benefits from Pilates.
There are many elite athletes that have turned to the Pilates method of training. Tiger Woods uses Pilates to improve his core strength, overall fitness, and his game!
Men will find that their flexibility will improve. They also may see it as a way to build strength and improve their balance as they age and are unable to play the sports that they love.
Men find Pilates just as challenging as women and I have seen men sweat while trying to perform Pilates movements. Again finding a qualified good instructor is key. If you find that you are in a class where there is not much focus and the essence of the movement is not being discussed then look elsewhere.
It is common for men to power through the movements, but the idea is to engage the core and activate the deeper muscles to stabilize the body.