Well that engine doesn't look that great, does it? If you look at the games that were developed with it, you can tell that it won't be really useful unless you develop a similar game.
Considering that there are plenty of free and open source engines out there like Ogre, Irrlicht, etc. which offer so much more, this offer ain't really that great.
I am sure there is some amount of customization allowed...... Its like saying 3DGS is only good for FPS games. I haven't tried it, I just thought it was interesting of the company to offer their engine for free.
