POWER is good, if used correctly
Have been involved with a client who has run POWER for many years extremely successfully. They still have several POWER 7 795 machines on the floor (out of maintenance but running happily). In over six years there has been only 1 hardware issue (caused by an overzealous engineer who pulled a wrong cable).
They run POWER VM and AIX and that is where some issues arise---not the products themselves but rather the lack of suitable skills to maintain and optimise both the virtualisation firmware and the OS.
Unfortunately none of the support guys ever played on a mainframe with MDF, PR/SM or MLPF and virtualisation on x86 is trivial (asking for trouble there).
They could have gone Linux but converting/testing/migrating over 300 logical partitions running AIX was a step too far.
Have got a couple of big POWER 8 boxen on the floor now.
The capex for thes products always look horrific cf other platforms but if you do proper costing anaylses over 6 years and rising, with guarenteed performance and availability POWER certainly competes against other solutions financailly.