I used it a few years ago when I was planning my track. Just for making all the sections that I found out i liked through experiment fit in the space I had. I found it easy enough to use even though it only had a German language pack.
The software is actually a full race management system including driver and car databases and sector timing, etc, but I think it needs a proprietary interface to the track. Overall it seems to have a lot to offer and runs sweet and stable.