They work on a competency based model where you either take a test, or do a project/paper (or both) for the class to pass it. If it takes you 3 weeks to study and pass the test it takes 3 weeks, if it takes 2 days you can pass the class in 2 days. The major benefit though is that you pay a flat price for a semester and then you can do as many credits as you want in that semester for a flat fee, so if you want you can get 24 credits done in one semester.
Additionally this isn't an ITT Tech or DeVrye type scam where they just push you through, a lot of the classes are based around industry certs as the final test for the class, and they give a through grounding in a lot of areas.
The flip side is they are very focused on practical job skills and not so much theory, I personally think it results in a more well rounded engineering student who is able to work in Networking, Software Development or Systems Admin reasonably competently.
Again I am a fun I recommend it, I wish everyone would start doing it because I think it is a game changer. Feel free to AMA if you have more questions about it.