I work for a large local government organisation who are about to embark on using SharePoint to replace our ageing intranet with an all-singing all-dancing collaborative sit
Being on the tail-end of building one of the largest public-facing, pure web CMS sites on MOSS 2007 (extranet/intranet/internet), I can say quite confidently that it absolutely blows as a CMS. Collaboration portal? Pretty decent. Document management? Not bad at all. WCMS? Awful. Horrible. Stay away.
Why? Sure you can make it work, as there are plenty of examples out there. You can look at the finished product from the outside and it might look pretty decent. But you have no idea how much pain, frustration, cost overruns, delays, and general badness happened to get there. Trust me, it can be quite a lot.