Cortex is one of the best RPG systems on the market. Its die-step system and rules for rolling dice for both characteristic and skill make this RPG stand out among other RPGs. The book is shy on illustration, but illustration is far more useful in a setting book and isn't truly necessary in a generic rules book. If you enjoyed the Serenity RPG, you very likely will want to have the Cortex book on your game shelf also as, due to its generic system nature, it includes a magic system and other information aimed at the usual genres of play. Character Traits add a rewarding element to roleplaying and those offered in Cortex are for the most part reasonable (in many games too many offered Traits border on the absurd); included are valuable guidelines for applying Traits to game play.
[5 of 5 Stars!]