The Canon EF 100mm f/2 USM Lens - meet the Canon EF 85mm f/1.8 USM Lens' twin sibling. Put these two lenses side by side and you will need to read the numbers to tell them apart. That is a good thing.
Putting numbers to the size and weight ... The 100 f/2 weighs 1.0 lb (460g), measures 3.0" x 2.9" (75.0g x 73.5g)(DxL) and has a relatively small 58mm filter diameter. This is relatively small and light - This is an easy-to-take-with-you lens.
The Canon EF 100mm f/2 USM Lens also shares the Canon EF 85mm f/1.8 USM Lens' fast and quiet Ring USM (Ultrasonic Motor) focusing. Tracking action sports is a task well-suited for the 100mm f/2 - AI Servo focus accuracy is excellent.
Contrast and saturation are very good - comparable with the sibling. The optional ET-65III Lens Hood is a wise addition to this lens - to retain the contrast and saturation with bright lights in/near the frame. Some CA is apparent at f/2. Wide open vignetting from the 100 f/2 will be apparent but not bad for full-frame DSLR users - similar to or slightly better than the Canon EF 85mm f/1.8 USM Lens' The 100 f/2 is one of the better lenses available in regards to distortion – expect only a negligible amount.