I'm at the point where I want to start integrating a physics engine into my game. In the past I've always used ODE but it looks like that project has started collecting dust and some of the old wikis on it have disappeared. With that in mind I'm looking at a couple new possible options. The requirements are:

- Support 3D and basic collisions (I don't need anything fancy)
- cross platform
- free for all uses

I'm looking at:

- Newton Dynamic
- Bullet
- ODE

Anyone have any experiences with integrating Newton or Bullet. I'm mainly interested around ease of use and integration since I'm sure either would do the actual math I need it to do in a performant way.