It's kind of like computer modeling for dummies, except it's not dumbed down at all; just made easy. It's free, though there is a paid version with some more features.
From what I have read and what I can see, this is a whole lot easier to work with than QCAD, which I use and swear by. And you can apparently do all but the most esoteric things QCAD can do. You're not lacking much, if anything even a moderately advanced user might want. NOTHING!