Jenny Rappaport had an interesting post today about the ideal length of debut fantasy novels. Good information to have. What I found more helpful, though, from a pure writing standpoint was her short lesson on how to write description. Here's what I took away from it: If you feel an overwhelming urge to describe things, the least you can do is blend it into the action of the narrative.
Take this sentence: Piles of trash littered the alley, and laundry hung from cords strung between windows.
Now this one: Cynthia picked her way among piles of trash and ducked laundry that had been hung to dry on cords strung between windows.
Neither of those are great sentences, but the second one is much more interesting to me because there's action. The character, Cynthia, is doing something. Even better would be if Cynthia tripped over some trash and got tangled in the laundry, showing her clumsiness. Or if she stole a shirt that caught her eye.
I'm not a fan of lots of description. In critiques of my stories, I've often been told I should describe how the characters look or what they're wearing or tell more about the room their in. My take on that is, does any of that information (a) advance the plot or (b) add meaningfully to character development? If it doesn't, I don't include it.
Does it matter whether my main female character has blue eyes? As far as I'm concerned, no, unless the main male character thinks her eyes remind him of the sea near where he grew up. Then it's character development.
So if you use description, make it useful to your narrative. Otherwise, ask yourself if you really need it at all.