dude, the sum of all is what matters, strong engine+"slow" gearbox+heavy car=? underpowered? its a big ol car, a good car, no mistake about that but again, its getting boring now, its underpowered compared to the 328i,
which is much lighter+same gearbox+strong engine.
The whole argument is that the 528i is too big and heavy for the engine, but you continue going on about open opinions- road tests, gearbox learning, comparing to other cars etc,. all pretty boring, you already said it was "underwhelming" which in the end was probably what you thought in the first place and that does it for me.
all it needs is a shot of 500cc more and it will be perfect