Pretty easy, in the grand scheme of things. It has its own GUI that takes a bit getting used to, but it's extremely robust, with a very clean interface that makes sense. Some of the workflow is a bit counter-intuitive, but you can pretty much start messing around right away. I have a ton of these ideas I'm working on, some of the stuff you can do is amazing. Compared to a 3D rigid body physics sim, it's like legoes. I only wish it had better support for vast numbers of objects, like a particle system. And that you could clone groups of objects with their dynamic properties. But I'm still learning