Cortex is a good system if you are looking for something that isn't d20. The way the system handles skills and attributes is good. I especially like the way that the GM decides what Attribute and Skill are linked, based upon the use of the skill. The skill specialty system is good, however, I think there should be a finite subset of specialties, which can be done by the GM -- but I would have like to see a base set in the book.
This is a good tool kit for running almost any type of genre, though it suffers a bit when it comes to fantasy. Though there is a suggestion and a few spells, it leaves a huge gap in the magic department. Also, scaling for creatures doesn't seem to work well.
Over all I would recommend it. Cortex does have a slight getting use to curve, mainly in resolving damage, but one the players get the knack of that its smooth sailing.
[3 of 5 Stars!]