The FPV as implemented on a PFD is only half a solution. The whole point of the original FPV was that it was displayed as part of the HUD to provide instantaneous flight path info and as such is brilliant.
When using it as part of a visual segment on say the 737, all it gives you is another piece of information about the flight path that you have to integrate into your brain and respond to together with the view out of the window &c.
I use it on runways with no visual or electronic slope guidance, and in IMC close to minima as a reminder where to look for the runway but not in other circumstances.