Samsung has begun rolling out an update to the Galaxy Gear that will bring over Tizen, the company's in-house OS, to the smartwatch. The update carries software version 2.2.0, and while the entire OS will be replaced, most users won't notice any visual differences. However, quite a few improvements and new features are to be had - improved performance and battery life, features such as an standalone music player (you can store music on the watch itself), customizable shortcuts for tap input, voice commands in the camera, among others.
I'm still waiting on the Tizen phones Samsung has been promising for years. Even though it's essentially 'TouchWiz OS' (in other words, cringe-worthy), it's still an alternative operating system I would love to play with.