Often times when Development Team are looking to do Code Review, reading the numbers out of Cyclomatic Complexity is one of the Top Priorities.
Cyclomatic Complexity is a formula for determining the varying logical paths that can be taken though a piece of code, thus determining a quantitative value for the code’s complexity. A higher Cyclomatic Complexity score means that there are a lot of code paths and/or factors that affect the logic with the code. One way to think about it is this: to fully unit test a method, you should have one unit test for each logic path – thus a score of 10 would result in as many unit tests. Wikipedia entry: http://en.wikipedia.org/wiki/Cyclomatic_complexity
Martin Fowler in his BLOG mentions how to approach reading the metrics and act most effectively - http://martinfowler.com/articles/useOfMetrics.html
Also, I find this as a great read too - http://www.wrightfully.com/thoughts-on-cyclomatic-complexity/
There are also some great publications on MSDN - http://msdn.microsoft.com/en-us/library/bb385914.aspx
A few MSDN BLOGS worth reading -