About three weeks ago it was multiple choice. The vast majority were AIM questions, a few relatively simple weather questions. There were also one or two crossing restriction/VDP questions. Basically, read the AIM, know how to calculate VDP/crossing restrictions, and know some basic weather (what sort of front produces a temperature inversion is the one I recall).
I'm 135 and I missed maybe two with a minimal amount of study (they pretty obviously ask you about things related to what you missed in the HR/Tech interview). It's reasonably easy. Also, aviationinterviews.com has a study gouge that will give you an idea of the sorts of questions, although I don't think any of them were verbatim what we got.
Best of luck.