While you won't become a developer based solely on Codeacademy, it is a good discovery tool to see if the logic and structure of programming appeals to you. The only failing of the free website is that it does not point students toward the next level of learning how to code. Back in January we did a night school series on learning how to code; the final lesson offers a lot of great resources to expand the basic kernel of programming skills taught. Codeacademy would benefit from a similar resource directory.
All in all, the best thing about Codeacademy is having an easy-to-remember URL you can send to relatives and friends who ask you about learning how to program.