It's the season of giving and man, has Unity been busy. Unity 5.5's release notes are a mile high, and even the compressed announcement has enough packed into it to make any Unity developer's day brighten up a little.
5.5 boasts many features, including Microsoft Hololens support, which was previously in preview mode. For those using in-app purchases, the interface for doing so has been reduced to zero code, all while supporting multiple storefronts, now including CloudMoolah. Visual Studio Code debugger support, a long awaited addition, is implemented for both Windows and macOS. Last in the notable additions are the particle and line rendering system improvements, which allow developers to do even more interesting things with them.
Check out the Unity Blog for more information