OK...I read all the reviews for this product (I had to look under each color individually to see them all).  I knew EXACTLY what I was looking for; I was looking for a layering piece that fit like a second skin and would not be bulky or bunch up underneath another layer.  The fact that these are "one size fits all" was a little scary, but I must say after wearing these that they will definitely fit a wide range of sizes.  I am very large up top, yet it did not cause the length to ride up at all.  I normally wear a M/L in tops, and I am 5'4".  It is small coming out of the package, but it definitely stretches to accomodate.  They are the perfect weight--not too hot or too cold.  I bought one to start with, and I liked it so much that I bought 4 more in other colors.  These will be my go-to pieces for the Fall/Winter.  On the downside, as other reviewers had noted, there was a strange odor to a few of them.  I chalk it up to coming all the way from China (have noticed it in other items).  I washed them all before wearing, and the odor is barely there, if at all, and since it is a bottom layering piece, I'm OK with it--it's not that bad.