So this.
In my experience, around 20% of developers are the kind of hyper-anal people who will argue endlessly about the stupidest details. Your chances of having at least one on any given team is extremely high.
In one case I (and everyone on tha team) lost literally 3 hours arguing over whether a particular boolean variable should be named something like 'finished' or something like 'isFinished'. And everyone but the one guy who had a hard-on about it conceded the point within the first fifteen minutes.
In some teams, management is wise enough to tell the hyper-anal guys they're not invited to other people's code reviews anymore. In a lot, they're not, and good lord can you waste ridiculous amounts of time on nothing important or useful that way.
TL;DR: I like code reviews in theory but in practice for most teams they waste much more time than they save.