For those of you out there who are looking to start learning about Mari, I'd recommend this video!
Here's the description:
cmiVFX has released their first video of The Foundry’s powerful next-gen 3D painting package, Mari. In this course, Mari Introduction, Bryan Johnson will guide you through all the steps of necessary to complete a professional-tier project. The course will cover topics like Mari workflow setup, importing and painting a model, and baking and exporting several photo realistic textures so they will be ready to apply to Maya. You’ll learn the basic techniques that will keep your productivity on track. After taking this course you’ll be able to begin working comfortably in Mari on your own. You will learn enough to bring in your own projects and finish them with quality results. This course is the perfect launch pad for starting your skills within The Foundry's Mari.