SQL Server 2008 R2 BPA is an excellent and often under-used, tool. The title is a little misleading but it does work against SQL Server 2008 instances, not just R2 instances.
I recently had the chance to use BPA against SQL Server 2008 Analysis Services. SQL Browser is disabled by default.
I entered the server\instance with the port number and ran the BPA tool only to be told that the incorrect SQL Server version was in use. Very strange.
I checked PowerShell 2.0 was installed. I also had administrative permissions on both the OS and SSAS instance.
It turns out that the SQL Server Browser service must be running in order to discover the instance. This is now filed as a bug which should hopefully be fixed in the next release.
The output of BPA is really useful and the rules point to knowledge base articles