The Nintendo Game Boy Advance SP is small, portable and inexpensive (retails from $60-$75). It boasts a laptop-like clamshell design that keeps the 1.6" x 2.4" screen safe. The screen is bright and performs equally well outdoors in bright sunlight as well as in indoor lighting and outright darkness. Young gamers will particularly like this model with its simple interface and easy to use design. Extensive users may find the design a little cramped -- with its narrow button composition, it tends to do a number on your wrists. One huge advantage is that the GBA SP is one of the few portable systems that's actually small enough to fit in a pocket. It comes in various colors to suite your taste. Plus there are lots of Game Boy Games to choose from.
The rechargeable battery allows for long playing time (up to 10 hours with the screen on bright, and 18 with it turned off), or you can simply plug in the AC adapter. Plugging in a set of headphones is recommended for better sound, but to do so you will need the Nintendo Game Boy Advance SP headphone adapter.
Note that the SP model is not the same as the original, inferior Nintendo Game Boy Advance.