Rewritten from the ground up with a whole new codebase, UI and GameMaker.
You can find all the features here.
Rather than purchasing modules, you will be able to purchase stand alone licenses for GameMaker Studio 2 on a per platform basis. For example, if you are only developing for web, you only ever need to purchase a web license.
At launch, a GameMaker Studio 2 desktop license (allowing export to Windows, Linux and Mac) will be available for a one time purchase of $99.99*
A Trial version of GameMaker Studio 2 will be available for free, to allow you to explore all of the new innovations on offer. The Trial version will come with limitations on the number of resources a single project can hold and does not allow exporting final executables.
A full list of system requirements can be found here.
Follow this Guide to sign up and get your hands on GameMaker Studio 2 for a first look.