So here is my review of Boost.Ratio *- What is your evaluation of the design?* It's a strictly (or at least as struct as possible) implementation of the standard proposal. Code is clear and easily followed. *- What is your evaluation of the implementation?* It's very OK and straightforward. I'll reiterate the question about providing MPL or Fusion adaptors as an optional features (unless I missed them :x) *- What is your evaluation of the documentation?* Good *- What is your evaluation of the potential usefulness of the library?* Ratio fills a gap in the MPl-like data type and enables new interesting design to be done. *- Did you try to use the library? With what compiler? Did you have any problems? * I tried it using gcc 4.4 and 4.5 and icc 11. No problem so far. *- How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? * I quickly glanced over the code as I knew it from its inception and followed it so I only had to look some new stuff. I tried some non trivial task , including some attempt at MPL like CT linear system solver using rational. boost.ratio proved itself useful in this task. *- Are you knowledgeable about the problem domain? * Yes. *- Do you think the library should be accepted as a Boost library?* Yes