Eurocontrol are introducing quite a lot of CBT into their ATC training. We recently had to do the ADP (Aeronautical Data Processing- i.e. the Maastricht computer system (MADAP)) CBT. It's a complicated subject at the best of times, but the frustration of having to listen to the voice drone on and on and on and on and on.... plus having no text to back it up was really, really awful.
16 of us did it, and without exception we found it more tedious than classroom lectures. I personally would have preferred a book/folder that I can read through, make notes in the margin, re-read paragraphs I don't understand, flick back to something that I realise I didn't understand the concept of after coming across something further on in the training.
To give them credit, they've tried to introduce these functionalities to the CBT, but NOTHING, and I mean NOTHING can replace the tried and tested method of pen and paper!
FYI, I ended up copying the CBT commentary down word-for-word, then taking it home and writing it up. I think I understand it better by doing that that I ever would have done working through the damn course without doing that. I'm not the only one who did that.
So, in a nutshell... CBT? Don't waste your time, don't waste your students' time. Just produce a book, and tell the students to go away and study it. Sorted.