This is the reviewers often pithy summation of the game, and is a good place to look for a quick overview of the title. Hardware is judged on different criteria, and thus different ratings. As with software, the Overall represents the product as a whole, and is not an average of the sub-categories. Value represents whether or not the hardware is priced well. This includes not only how the price compares with competing products, but the extent and quality of the packed-in software, if any.
Features describes the most about the product.
For a video card this could be it's abilities and speed, for a joystick it's feel, options, and ease of use. Compatibility describes how well the product works with a variety of computer setups and various software titles.