I've never taken the course so I can't say from experience whether it's good or not, but I can tell you that there are only a few types of questions and topics covered in the GMAT. If you can learn about the types of questions and the strategies to attack them efficiently then you can do well on verbal. The point is that I think it's possible to learn the types and strategies over a two day course. But it would only serve as a beginning point - you would still need to put in many more hours to see how those strategies are applied in practice. That you cannot do in a two-day course. Do not come out of the course expecting your score to jump from V25 to V40.

I should hope that by the end of the course, you would have the knowledge and skills necessary to do well - how you leverage that information depends on you.