Imagine is really good, besides the difficult learning curve. I remember back then, it was once a tough competitor for the highly praised Lightwave.
As i see it, still Lightwave was difficult for me. I liked Cinema 4D and the incredible simplicity of Tornado 3D.
By the way, the last version of Imagine was 5.19, and it is still supported and sold by the developers.
On the other hand, you can get the PC version for free at the website mentioned above!