I write fantasy (see my profile), and I tend to be light on description, at least by the standards of the genre. My attitude is "as little as the reader needs to not get a false impression of the scene". I never do big chunks of description. I always try to anchor it to what the point-of-view character can perceive at the moment. If I have more than about three sentences of description, I'll break it up with the character doing something or saying something or thinking something.
People read fantasy for the sense of being in another world, so details can be important, but I hate it when writers bring the story to a juddering halt to try to impress you with a page-long description of a castle or a marketplace. I picture the characters standing there, tapping their feet, waiting for him to finish. I've seen enough castles and marketplaces to picture what this one probably looks like. If you brought the characters here, it's because something's going to happen here that's important in the story. So get on with the story already!
This is the first passage with a lot of description in Death & Magic, from chapter 2. (There's little description in chapter 1, because it's set in a place where the main character has lived half her life, so she doesn't notice the scenery any more. You can get away with more description of a place the character has never seen before.)
Adramal took her leave of the barge crew and stepped onto one of the wharves at Kyer Altamar’s western docks. Beside the wharves stood a row of tall wooden buildings - warehouses, a man on the barge had called them. Their height rivalled the tallest trees that grew near her home. She shouldered her pack and walked along an alleyway that led past the nearest warehouse and into the city proper. Nobody on the barge had known exactly where the school was, but they’d thought it would be easy to find someone who did.
The alley opened onto a broad, cobbled street, crowded with horse-drawn wagons. The horses stood patiently as burly men transferred goods between the wagons and the warehouses. Adramal gasped - she’d never seen so many of the animals in one place. The wind shifted, slapping her in the face with their smell. Crowded into such a small space, they bordered on overpowering. She placed a hand over her mouth and nose as she hurried past them.
At the end of the street stood a large wooden building with a little barrel hanging over the door. This, Adramal recalled, meant the building was a tavern - a good place to obtain information, the barge crew had told her.
The tavern’s interior was a long narrow room, with a row of booths running along either side. Quiet conversation reached her from further in. Smoke from candles lingered among the rafters, and a strong smell of beer hung in the air. Adramal hesitated. The crew hadn’t said anything about beer. Like any intoxicant, it interfered with a wizard’s ability to perform magic, and so the teachers at Thuren had warned her to avoid the stuff whenever possible.
If you pick out all the descriptive details there, I'm telling you quite a lot, but (if I've done my job well) you don't notice that I'm telling you a lot, because other things are going on at the same time.