I agree with Rakushka about how the quality varies a lot. One other thing I'd add is that as their quality has stayed the same or even declined, the prices have continued to go way up. That being said, at least half of my clothes and my husband's clothes come from J.Crew. They fit me and my style very well. And the quality is still much higher than average, I think.
Students and teachers get 15% off, even on sale items, so I always take advantage of that. You have to go to a B and M store to use the discount, though (they will order catalog items for you there and ship them for free).
For the record, I'm 35, a pear/hourglass shape with broad shoulders and heavier legs, and take mainly 10s and 12s in J.Crew, 32 in their jeans. I also wear 10s and 12s in Banana Republic if that helps.
ETA - J.Crew often has final sale online, but I have found that in store sale items are rarely final sale. I don't buy anything on final sale.