If you like 3DGS, DON'T download Unity. You will never come back to it.

Yeah, i think so !

I use it and some points that you will find big :
- Cross Platform
- Browser support for 3D games with big power : island demo
- Simple physics and properties on a object by clicks on a
panel properties in the world editor : big workflow !
- shaders : No coding , No shaders search etc ...some
clicks apply to the mesh , textures assign graphically and
it's running
- Ambient occlusion as a built-in feature
- All complete terrain tools included in world editor really
rocks !
- Iphone version rocks a lot : lot of selled titles !
- 360 coming !
-choosen by Funcom for their next mmo !

It's like having very advanced versions GED, MED, WED and lot more in a one world editor : all very polished and user friendly.

And Free :
I think also 3DGS can't compete with it's commercial version !
Why paying when you have lot more advanced , lot more professionnal for free ?