Quantative Concepts Excellent, Verbal Mostly Good

Strengths:

Well organized curriculum. Excellent coverage of quantitative concepts. Verbal strategies are mostly excellent.

Would make the product better:

Personally I felt like the verbal explanations (roughly 5-10%) were occassionally not in line with OG. For example, TTP mentions some things about bad comparisons not being the correct answer, but in OG I saw a few times where it was correct.

Overall, TTP is a great starting point. I used it for about 200 hours over a 1 month period (completed everything except the easy chapter tests). This is the first, and very likely last time, taking the GMAT.

My first two practice mocks (no studying besides the free starter kit) were 605 and 655. TTP quantitative concepts covered 95%+ of the quantitative concepts I saw on OG/the actual exam. The verbal, although there were some parts that I disagreed with, did have some very valuable strategies for tackling questions and in combination with OG was enough to get a decent verbal score. The best verbal strategy overall they had, I would say is learning how to eliminate incorrect answers.

Note that I am not a native english speaker by definition, but I've studied/worked long enough in English that I would consider there to be a small difference at most with a native speaker. I also have an undergrad in math.