I'm a huge fan of description. Description helps the author really communicate a scene, action, or character to the reader. When I read someone else's work, it is the thing that will often make or break a book. Yes, I can get into an interesting plot line, but if the author can't articulate how a place smells, looks, and sounds, my respect for them goes down the tubes.
When I say respect, what I really mean is, I think they suck.
While I don't want to have an actor take the place of my imagined character, all readers need direction in what to imagine. What color is the character's hair? Eyes? Clothing? Do they have perfect teeth? Are they chiseled? Lanky? Fat? Stout? Gigantic? Stick-like? As a reader I need to know these things, or at least, the most important things. BUT when it comes to a main character, all of these things are important. The main character should be the least fuzzy of all, and therefore, the most clearly described.
A lot of authors have difficulty with description because they haven't taken their imagined character and put them on the page. They think they've described the character because they've imagined the person a thousand times both waking and sleeping since yesterday. But the reader hasn't. If you, as a writer, haven't yet mastered the subtle art of communicating what you imagine through words, it is imperative for you to have someone read your work, and then reread your own words. A second pair of eyes will always give you helpful feedback like, "What the hell is this supposed to mean?" or "Who is speaking here?" or my favorite written feedback, "???"
By the second time you have read your work, you'll see where you missed the boat, what needs to become clearer, and how to generally be a better writer.
Keep in mind, even if your first draft sucked (which let's face it, is pretty likely for any first-time writer), even the best authors have a drafting process. Many people take four, five, or even ten drafts before they feel comfortable sharing their writing publicly. And if you are one of those lucky people who has an agent and publisher, they may help you edit your manuscript again. Hopefully at least one of those times, we'll find out that your main character wears, eats, sleeps, and how his or her face looks when they're annoyed. Just saying. The small stuff is important, and it's all small when it comes to description.