One of the biggest pros is that reviewing code keeps you up to date on the current state of the code base. I have, at least briefly, read and understood every line of code in our teams code base. I might not remember it perfectly, but I still feel like it is fairly easy to dive into and change any part of it, even the parts I haven't worked on in a while. This, plus occasional informal architecture standups, means we have a lot of flexibility in terms of developer allocation for tickets.