I originally bought a Medium. I'm usually a Medium in everything Nike and a 27/28 for most denim. Had to exchange for a large because it was wayyyy too tight around the hips. The overalls do not have a "shapely" bottom. I was definitely going for a loose fit and it looked and felt more appropriate after the size exchange.
The material as of now seems pretty durable but the straps did twist a lot throughout the day but there is definitely a look of uniqueness to them as I had people stopping me all day asking me about the overalls :)