Simple but Profound
First of all, I enjoyed reading it. It was an "easy read" in the sense that it was basic. I would, therefore, conclude that your target audience is largely the "churched" people to help them to see the value of Torah in a conceptual sense. But even being "basic" there were still some very choice parts to it.
I'll share with you specific issues that stuck out in my mind as I read it.
1. I liked what Aaron wrote on p. 33, "The letter to the Galatians is not against obeying the Torah; it's against using the ritual of conversion (circumcision) to become Jewish as a means of salvation." Good point. Seems kind of simple, but there's a very profound truth hidden there. What about "using the ritual of conversion (circumcision) to become Jewish" for other means, such as facilitating the return of the geulah, helping to establish minyans around the world, standing firm with our Jewish brothers, etc.? Clearly, Sha'ul doesn't address these issues, and I think we would be hard pressed to find arguments to the contrary in his writings. Something to think about.
2. I appreciate and concur with what he wrote at the end of p.39 and start of p.40 regarding Christianity's responsibility for facilitating the current "anti" thinking of Yeshua in the orthodox Jewish world. Very true.
3. Good points on discipleship indicating its historical context of "imitation," not "observation." It's about doing, not just studying what someone else did or does. This could be really emphasized in future material.
4. Enjoyed Aaron's treatment of Paul, especially what he wrote on p. 55. Either, he's a false prophet; Hashem is nuts; or we've got Sha'ul wrong. Yes indeed. Clear, dramatic, and well put.
5. His comment about 2 Peter 3:16-17 and bringing out the meaning of "lawless" as not being anomia, but rather athesmos is very important. This explains why so many still "don't get it." They refuse to immerse themselves in the customs of Israel, preferring to think of those things as being "mere tradition" and not Torah. This too can be developed further, i.e. the importance of customs and traditions of Judaism. It also ties to the idea of discipleship, to truly imitate Yeshua in all things.
6. I liked his summary of Romans 2 in what he wrote on p. 62.
7. On p. 67, Aaron wrote, "This is why the religious leaders...tested and questioned him. They had a right -- even a responsibility -- to do so as leaders..." Very interesting point. I liked that. Again, it helps dismiss anti-Semitic thinking that all the Pharisees were out to get him. We must be very careful when imputing motives to people who lived 2000 years ago when we know very little about them, unless the text expressly indicates their purpose. Not all Pharisees were the same.
8. The challenge to start from first principles with Torah (p. 69-70) and find support for the Messiahship of Yeshua is going to be very challenging indeed. Important, but very challenging. I'm glad he said it. I've also focused on that point in my teachings and personal life recently. We must go in order; not backwards. Does the Torah support a Messiah like Yeshua? I believe so, but it's often in hints and mysteries of Torah (about Messiah ben Yosef), and not in plain sight. If people don't have solid support for their beliefs (other than the fact that they "grew up believing it" which is no proof for anything at all), then when their false notions are pulled away from them and they "go flying" so to speak, they will have nothing of truth to replace it with to stand on. They need truth to replace their false foundations of assumptions. This also outlines further work to do.