I have purchase this calculator about four years ago on ebay, because I struggled so much in math. This calculator even has usb connectivity for tranferring data and installing applications. This calculator is for the greater level of math or physics courses, this calculator is great use if you is currently taking a math class like calculus, actually this is absolutely essential for anyone taking a Calculus classes (Calc I, Calc II, Calc III). But if you doing a class like Algebra then I would recommend you to stick with the TI-83 and don't worry about spending the extra money on the TI-89 Graphing Calculator, because this calculator has so much extra features that you would probably get confused on what button to press for that or that.
Oh yea let me tell you alittle something about the graphing on this calculator, it is absolutely amazing you can graph in 3d and graph in 3d rotations. If you need to do alot of graphing you have to get the Texas Instruments calculators, I know it may seem like it is alittle to much for a calculator but it is worth it and it will help you alot.