The main argument in favour is that it will cut the cost of your development process, by alerting you as soon as possible that you have a broken build or failing tests.
The problem of integrating the work of multiple developers is the main danger of growing a team. The larger the team gets, the harder it is to coordinate their work and stop them messing with each other's changes. The only good solution is to tell them to "integrate early and often", by checking in small units of work (sometimes called "stories") as they are completed.
You should make the build machine rebuild EVERY time some checks in, throughout the day. With Cruise Control, you can get an icon on your task bar that turns red (and even talks to you!) when the build is broken.
You should then do a nightly full clean build where the source version is labeled (given a unique build number) that you can choose to publish to your stakeholders (product managers, QA people). This is so that when a bug is reported, it is against a known build number (that's extremely important).
Ideally you should have an internal site where builds can be downloaded, and have a button you can click to publish the previous nightly build.
