I'm 5'10 and very slender, so I was worried about the length of the jacket and the arm length when I ordered a small. When my (black and hot pink) jacket arrived in the mail, I was pleasantly surprised by how well it fit me! The sleeve length was just right and it wasn't too huge in the waist, as most ski jackets are. The inner jacket is zipped and clipped into the outer jacket, making it very easy to pull them separate when needed, but it still feels like one jacket when all together. I haven't worn it out skiing yet, but it seems pretty perfect!
The only thing I would wish for would be more pockets- I really like having pockets inside my jacket for things like credit cards and cell phones.