Pretty good and would make an excellent supplement to MGMAT SC
Strengths:
1. Concise
2. The content is organized in a very effective manner
3. The Idioms List!
4. Overall, the organization is crisp and concise
Weaknesses
1. It is a PDF.
2. There are no practice problems or associated content (there is a separate question bank available now)
3. It doesn't go into too much detail.
LINK
Link2