Portal 2 is one of those perfect sequels that improves upon the original in every way. Narratively and mechanically a perfect experience and likely the furthest the portal gimmick can be taken without dipping into convolution.

The lessons learned by the industry from Portal 2 are in the form of narrative and environmental story telling rather than game design and level design due to the games laser focus on its central mechanic not being able to translate to anything else.

An absolute must play.