With no reviews, I was skeptical. Also, I didn't know what effect a little polyester might have on the jeans. The answer to the last question is NONE; they feel and act exactly like 100% cotton jeans.  I own a lot of Levis 514s--regular and in colors. These by far are the best fitting. I don't have the greatest tush (in fact very little at all), yet these fit nicely, not sagging back there where I have very little. Highly recommended.