The Learning Edition still costs about $10 for shipping so it's not exactly free There's a $0 download edition too. Version 5 isn't available yet, but will be hopefully soon. Maya the program is very popular amongst the big studios because a) it's very flexible and expandable with its SDK and MEL and b) it's robust c) it's one of the most featureful - the unlimited version comes with hair, cloth and fluid simulation. Even the $0 PLE comes with soft and rigid body dynamics.