Thanks for the review! I definitely had the sense that Rosen was doing a lot of hand holding and handwaving—it’s certainly a very introductory text. I’ve read both Rosen and Eppstein and actually found Rosen better. The discrete math class I took in college used Scheinerman’s Mathematics: A Discrete Introduction, which I also found to be worse than Rosen.
At the time I actually really enjoyed the fact that Rosen went on tangents and helped me learn how to write a proof, since I was relatively lacking in mathematical maturity. I’d add that Rosen does cover proof writing earlier in the book, but I suspect that MCS might do this job better. Given the target audience of the MIRI research guide, I think it makes sense to switch over to MCS from Rosen.