Two sections: General Operating Subjects (GOS) covers general stuff (meteorology, regulations, charts, etc) plus the FOM, and has a written exam for each subject that you need to get 80% on to pass; after two fails it gets locked although you can talk to an instructor to get it reset. This section of CBT was made by non-pilots in the nwa training department and the instructors at Compass say it was pretty horrible in the beginning and they've been continuously working to improve it. Still some rough edges...I would say the main problem is a disconnect between the material presented in the CBT and what's tested on the quizzes. I'd recommend reading the appropriate sections of the FOM before taking the quizzes rather than relying on the CBT to teach you everything that'll be tested.

The E175 CBT was not put together by Compass or NWA, and is pretty decent. Only complaint is that some of the stuff they taught is wrong for the E175 (used E170 numbers). There are short quizzes throughout which do not impact your final grade. There's a 80 question multiple choice written exam at the end, though. It merits studying up for.

Hope that helps.