This is a mistake that I made a lot when writing In the Days: A Tale of the Forgotten Continent for the first time, and it's one that I hope never to make again.
Have you ever noticed how some books suck you into the rich, detailed world, feeding you images of everything around the character as he/she moves? You get all the sights, sounds, and smells, and the book is a much more complete experience because of it!
And then there are writers who fail to give you all of the details of what's going on around the characters. You get a small glimpse of the city/terrain in which they find themselves, but there is little detail added as scenes change. It forces readers to use their imagination to fill in the details, and the book is just a little poorer because of the lack of imagery.
As a writer, your job is to help people see the world that you have constructed in your head. You want them to be transported to this world with you--whether that world is Middle Earth, your own fictional continent/planet, or downtown New York City. You have to feed them details of what the world is like in order to give them an idea what they should be picturing in their head.
Here's an example of what I consider to be sufficient description:
Business was booming at The Iron Arms tonight, though every night found the tavern full to bursting. Thanks to its proximity to the docks, the alehouse saw a steady stream of day laborers, roughnecks, and roustabouts hoping to quench their thirst at the end of a long day.
Drunken tradesmen and merchants filled the tables, while tired dockhands nursed tankards overflowing with frothy ale. The smell of sawdust and stale sweat hung heavy in the air, and peanut shells mixed in with the wood shavings on the floor. The sounds of clinking glasses, shouting patrons, and loud conversations filled the air.
Barmaids wended their way through the bar patrons, delivering drinks with a hearty laugh and a hard slap to roving hands. Their bodices looked too tight, but the men filling the bar approved of the scanty outfits. Indeed, the wenches found themselves fending off advances from all sides, though occasionally one would hustle up the creaking stairs with a customer for extra special customer attention.
(excerpt from The Last Bucelarii, Book 1: Blade of the Destroyer)
It gives you an idea of what the place looks, smells, and sounds like, and it helps to set the tone for the ambience (the presence of roughnecks, the loudness of the bar, the customers leering at the wenches, etc.).
Writers, fill in the details! Don’t leave us readers hanging in a colorless, odorless, soundless void where our imagination is forced to fill in the details, but feed those details to us. It makes for a much better read!