I would caution that if you have any deprecated syntax in the database's views and stored procs (SQL-89 joins for example), changing the compatibility mode can cause them to break. You want to carefully consider any changes to your databases' compatibility levels. Just like newer syntax is won't work on older compatibility levels, some deprecated syntax will not work with newer compatibility levels.

If you're not sure whether this applies to your database or not, Microsoft's Upgrade Adviser Utility is a good place to start. Unfortunately, if your applications have a lot of in-line SQL, this process can become significantly more painful.