The casual and indie versions have really deep feature cuts. Much worse than feature cuts of other engines. So actually you have to buy the 1,500 $ edition.

GC advertises the easy art workflow as the selling point. It even claims to be the worlds best engine in this matter (even better than Unreal3 or id Tech). But in indie terms the direct opponent is Unity3d. So it makes sense to compare both.

The presentation of GC is very bad while Unity is quite good. The documentation of GC is bad at the moment. The gallery looks bad and there are no projects at all. There is no availability on other platforms than Windows.
With all this in mind it should be way cheaper than Unity or simply much better if they share the same price.

Currently I see bad chances to sell this technology from a marketing point of view.

Nevertheless: The features read very good. The only feature issue is: I found nothing about scene management. But scene management is the most important fact of an engine technology. This is what an engine should do: render and occlude contents as fast and as good as possible.

I will watch this more closely.