of requirements, you'll have the benefits of email pass-around reviews (works with multiple, possibly-remote developers, minimizes interruptions) but without the problems of no workflow enforcement, no metrics, and wasting time with file/difference packaging, delivery, and inspection.
It's impossible to give a proper list of pros and cons for tool-assisted reviews because it depends on the tool's features. But if the tool satisfies all the requirements above, it should be able to combat all the "cons" above.
So what do I do?
All of the techniques above are useful and will result in better code than you would otherwise have. All of our experience with peer code review has been poured into articles and books and Code Collaborator — software for tool-assisted code reviews.
We have data that simultaneously shows how to maximize peer review effectiveness while minimizing amount of time spent doing it. This is the subject of our next article.