Super Mario 64 is a classic video game and basically invented 3D in video games. Although it is a fantastic game, it hasn't aged well in a few areas and I will explain my point below.
Princess Peach has been captured by Bowser again. That is the basic plot of Mario 64, but the real stories are told through gameplay and mission structure. You have to collect stars to save the princess and Mario 64 gives you many missions to collect these stars. Every level has multiple missions that tell small stories within them and every mission is very inspired, as well as unique. The mission variety is unmatched and the worlds they take place in are fantastic. Each mission challenges the player in their skill and are perfectly structured. Each level is varied and has unique gimmicks and details. The worlds are what makes Mario 64 shine. There are a few levels that are linear and do not have many traversal options, and these levels are flaws of the game. Compared to the amount of inspired, perfectly made levels there are not many bad ones, but they are still there. I won't spoil the levels or mission but the majority are perfect, with a few exceptions.
The platforming in Mario 64 is very complex. You have so much freedom to platform where you want using different skills and experimenting with them. The variety in jumping mechanics and moves allows a sense of freedom within the game that not many other games can replicate. The only issue with this freedom is how janky and the inputs being are difficult to land due its control scheme. There are also some mission designs and levels, as stated above, that have not aged well and combining this with the janky controls make for a less enjoyable experience at some points. Sometimes you have to be overly precise with your jumps and will not land in the direction you want. Enemy types and obstacles are varied and create a solid gameplay experience as well. Even though I have issues with the platforming, once it has been mastered the game can feel fantastic and is very enjoyable for the majority of the experience.
Super Mario 64 is a classic due to its innovation in 3D games, level design and platforming mechanics. Some elements have not aged as well, such as controls, some level designs and overly precise platforming, but this does not mean Mario 64 is bad. Super Mario 64 is a classic and should be looked at as a platforming masterpiece in most areas.