Comrades is excellently written, and it is most probably the best RPG I've ever read. While the text is rather straight-to-the-point, it gives everything you need to play (from the tiny details of the game mechanics to broader aspects of role-playing). This was my entry point to the PbTa system, and I cannot feel more thankful to W.M. Akers for that. The game really "invites" you to embrace the philosophy of that system, and tells you why it is awesome to play.
A possible caveat is that, for some, the "wording" may be too narrow. I mean the fact that is written somehow based on historical (left-wing) revolutions. In my group, we have played in a "rebelion-revolution" context that did not have any left-wing implications, without altering the system at all. The game worked perfectly. I beleive one could have overcome that just by being more "general" in the text and the playbooks. But I believe it is a matter of taste. In any case, this should not be an excuse for not buying the game. Just do it, and play whatever you want to play. You will not regret.