Configuring rules was simple on a project by project basis - not sure how easy it would be to configure on a wider basis - so that all the rules are shared across many solutions. It is theoretically possible to add a custom rule making use of an SDK and code editing - there is a tutorial on this.
The errors returned are grouped by project, making filtering really easy. It even gives an ability to automagically (their word not mine) correct code errors and violations. When I tried this, my project didn't build any more, although I suspect this may have had something to do with dependency issues - any altered code through this process was commented, such as
//ENCAPSULATE FIELD BY CODEIT.RIGHT
The errors returned for my test project didn't seem to be to as granular a level as I've experienced previously with FxCop - this was a concern.
There is a command line version available which can be incorporated into an automated build process.