Big dittos on the previous comments! I bought mine because I wanted something that had the feel of the M16A1 I carried in Vietnam but didn't want the power and ammo expense of a regular AR (I got one out of two of my wishes at least!). The 15-22 can accept almost any accessory that can be hung on a "real" AR, even a new performance trigger assembly is pretty much a drop-in. The S&W site has a dedicated 15-22 forum that will fill your head with some of the possibilities for customizing the gun and is a good source of specific information.
It is a great little gun, you will enjoy it!
"History teaches that war begins when nations believe that the price of aggression is cheap." - Ronald Reagan