Several relies here suggest that CNAMEs increase DNS load. This made me curious. I fired up wireshark, inspected a request for a CNAME, and at least in our environment the result was returned in one record. Which brings Knuth's aphorism to mind here: "premature optimization is the root of all evil".
I like CNAMEs, but mostly for their psychological effect. They encourage people (like me for instance) to uncouple server names from service names.
Our environment has several SSL certs attached to opaque server names (which we've quit doing). CNAMEs work much better here. In every place I've worked migrating services where the server name is tightly coupled to the service is a headache. CNAMEs give clear conceptual line of separation.