I have taken two classes so far, both at Pocono Raceway in Long Pond, Pa. This was, by far, the best money I ever spent on anything motorcycle related. In short, YES, you should sign up for a class, and you will learn an amazing amount. You will also have a blast doing it.
One eye opening thing for me was the difference between track riding and street riding. Also, I saw many examples of the old adage "it's the rider, not the bike." After taking the classes, your riding will definitely inprove, I know mine did. You'll also meet a lot of great people.
Although it may seem like a lot of money to spend, for only a day or two, the dividends will pay on every ride thereafter. Sign up for two back to back days if you can afford to.