My husband wanted this for Halloween and tried it on in a real store before buying it cheaper on Amazon.  He is about 5'9" and around 180/190 lbs, a very average size, definitely not an extra large.  Happily, he knew he would need this size having tried it on elsewhere otherwise he would have ordered one much too small.  Even still, the inseam was a little tight - the crotch could have been lowered to make for a more comfortable torso fit but it wasn't awful.  I feel like if I were to borrow this costume next year, it would also look good on me (female, 5'5", 125 lbs), just a little baggier which is what I'd be going for in this costume.

All that to say, I think these sizes run very small so if you're much taller than 5'9" or have a small gut, I would not think it would fit well.