Yes, and no, but mostly yes. Of course I can't speak to the "good" part because I am obviously very biased, but the course is one that specifically targets skills that are important to a concept artist.

Yes in the sense that what we cover here, spatial reasoning, is an extraordinarily important skill to develop in order to do the tasks that concept art demands. Rather, it is more accurate to say that it is what allows one to draw from their imagination, and that is the bread and butter of concept art.

No, in the sense that concept art specifically also requires the development of other skills, and so it is not a one-stop-shop to becoming a concept artist, just as it is not a one-stop-shop for any other specific use of the skills we develop. Students will have much more to learn beyond this. In the case of concept art, there are many other skills that are necessary (design, which is its own family covering other specific areas of study, being the main one), but depending on what kind of concept art (character design, vehicle design, environment design, prop design, etc.) you intend to focus on, there are many, many other skills that you will need to develop.

At the end of the day however, Drawabox covers what I feel helped me the most in developing my career, and since concept art was my main focus in my career, what we teach here does align strongly in that direction.