This is probably the greatest Platform game in existence. Following on perfectly from it's predecessors, once the tricky (well not so tricky, but I hadn't been playing N64 for long before this) controls are mastered, you will be doing bounces off walls to get extra coins in no time. Where this game really shines though, is in the level design. Each level really requires thought to complete fully, and some of the levels are just totally brilliant (the Haunted Castle for one).
Summary: The pinnacle of platform gaming, it can all only get worse from here (at least 'till Mario 4)
Graphics: 9 (sharp, but too colourful)
Sound: 10 (It's-a me, Mario!)
Gameplay: 10 (The King)
Longevity: 10 (You will be playing this for a LONG time