Good points. Can't emphasize enough the need for annotations and smallish patches. The worst for the reviewer is a 2kloc patch touching several dozen files with

Good points. Can't emphasize enough the need for annotations and smallish patches. The worst for the reviewer is a 2kloc patch touching several dozen files without any annotations. Positive culture is very important too. Invariably I found that the best way to start a discussion is with a question: "why did you implement it that way?" instead of "this code is wrong/bad/unreadable". Another mistake: starting with trivialities such as deviations from coding style. Spotting stray tabulation is easy, spotting a bug or suggesting better architecture is hard. Lastly, remember that the author has got something working and your suggested changes can introduce bugs, so this possibility should be weighted against potential "improvement". Giving a good code review is as hard as writing the code in the first place.