Decipher does an excellent job with the books. The system mirrors d20 in many ways, especially in the use of Target Numbers (ala DCs). It is quite easy for a d20 player to pick it up and run with it as it stands or you can put the extra work in it and convert it to d20. I would, however, just go with the CODA system because of its ease to comprehend.
Although I don't go into the game mechanics much, I did do a review on the two core books in the March issue of d20Zine! which you can download from my site. You may want to look them over.