The main problem with Kre-O, at least from my viewpoint, is that the sets are expensive. Transformers, G.I. Joe, Star Trek, and Battleship are all licensed sets and therefore have a premium attached to them beyond the cost of the pieces. Now there's a new line, called Cityville, and it's affordable.
This is a review of one of the smaller sets. It cost $8.99 at Toys'R'Us for 104 pieces.
Now for the questions.
Can you build a frame, or frames, right away? Looks like I could build one of my Spider Mecha from this set. (+5)
Is it below, at, or above the golden ratio? Below ($0.09 per part). (+5)
If you don't want build a frame right away, does it have parts you should be able to put into use elsewhere? Yes. (+5)
Does it have more than a handful of immediately useful parts? Yes. (+5)
This yields a score of +20 or A+. Winner, winner, chicken dinner!