Why GUIDs aren't so Good as SQL Server Primary Key

My informal poll of fellow developers reveals that by about a 4 to 1 margin, we are all using UNIQUEIDENTIFIER primary keys. Very Bad Idea.The GUID (UNIQUEIDENTIFIER) datatype is a wide column (16 bytes) and contains a unique combination of 33 uppercase and numeric characters. As the primary key it will be be stored in a clustered index (unless specified otherwise). it will be the page pointer