I would say that it depends on a number of factors. First, how much are you aware of how you configure and maintain the specific versions of SQL Server that they will be looking at? Then why are you doing SQL RAP? Is this a really good risk assessment to demonstrate to management that everything is being done right, or to find out where you are right now, to rectify the situation and find areas to learn more about the product, or not? from the above?
I had SQL RAP done at the end of last year, and I can tell you about personal experience, you will receive from it as much as you are open for training. If you have a cluster, be prepared to open your eyes to areas you have never thought of looking at. A visit to SQL RAP has four different steps, or at least mine. First they collect data from your SQL servers using pssdiag and a bunch of other neat tools that leave you with copies of most. Then they analyze where they take the data and conduct a very thorough analysis and generate reports and recommendations. Then they sit down with you and the leadership, if you have chosen so and go over everything that is good, what was, and what was bad. Then, in the last part, they sit down with you as the database administrator and teach you how to use the tools that they used, and that they can leave copies with you. They go through the PAL Tool, SQL Nexus and some others, and make sure that you know how to use these tools for self-analysis. Best of all, they leave you these truly detailed reports, which you can use as a standalone test to create new environments in the future.
Is it worth it? You probably can't say it until you're done with it. For me, I would recommend it to anyone who wants to learn more about implementing SQL Server "Best Practice", and who would like someone to learn the time from a senior Microsoft specialist.