Some people will swear by hop extract while others will be the total opposite. I bought some Cascade to try as a substitute for lightly dry hopped beers but haven't used it as yet. Unopened it will keep so I'm not panicking. I've heard that the hop extracts can improve head retention too but as I say, not tried it yet and I will only use it as an alternative to dry hopping. Got mine from the Malt Miller Nelson have been out of stock for a while. http://www.themaltmiller.co.uk/index.php?_a=viewCat&catId=25