My clients love Powerplay. Almost all of them use it. It is very good at what it does, and as an OLAP data source it is relatively simple to design. But Powerplay as a tool remains stuck in time. It has changed very little since I was first trained in it in 1999. Is Cognos Powerplay to be eclipsed by the more modern OLAP technology of Cognos TM1? TM1 has been billed to me largely as a replacement for Cognos Planning, and not intended to replace Powerplay. But if you read about the OLAP technologies that will be discussed at IBM Information on Demand, many refer to TM1 and ROLAP, but none refer to Powerplay.
Many Powerplay users remain stanchly loyal to their tool. They insisted on (and eventually got) Powerplay Studio added to the next generation Cognos portal to use in place of Analysis Studio. When I hear Powerplay developers speak of their experience with TM1, I hear of frustration with the complexity and difficulty of working with it. In contrast, Powerplay has always been the simplified tool.
Of course, simplicity has its cost. Powerplay is unable to do some of the more sophisticated modeling that TM1 is capable of. TM1 offers faster cube build time, in-memory calculation capability and complex modeling options. But do Powerplay users want (or need) these things? Will they insist on their Powerplay cubes as they insisted on Powerplay Studio? Only time will tell.