Is it useful ?
If you have only played partially with SharePoint like only using some WSS features or only used it for a specific and limited task or for a limited number of users then CMS Watch's report will provide you with the insight to go (or not go) further with SharePoint.
The main advantage and strong aspect of this report is the detailed analysis provided on a "per feature" basis. Eight different Business Services in SharePoint are reviewed, discussed, and analyzed: collaboration, Enterprise Content Management, Web Content Management, Portal Services, Business Intelligence Platform, Forms Processing, Enterprise Search, and Application Platform.
For each of these services, pros and cons are reviewed and discussed into much detail while providing insight as to better use (or not) SharePoint in a small or large enterprise environment.
The report also contains a nice section about evaluating customization and additional development which provides excellent hints about what should be taken into consideration.
All in all, this 195-pages long report is a kind of a must-read that can spare you days of consultancy just to arrive to the same conclusions for a higher price. Of course this report will not decide for you but it will make you understand why you decide for or against SharePoint (MOSS).