The premise of "Grand Piano" is a very interesting one. A concert pianist with stage fright is getting blackmailed into playing a perfect piano concert, or he will be shot. A musical version of "Speed", with a bit less action, but a much more thrilling atmosphere, undermined by a dramatic orchestral soundtrack.
Sadly though, the premise is about everything this movie has to offer. The reason behind the blackmail is kind of forced and only serves to allow the premise, without much deeper thought behind it. This pattern can be transferred over to the whole movie. It's not bad, but there are an immense amount of missed opportunities. Instead of letting the orchestra a similar, overly dramatic style of music for the whole film, it could have been more dynamic and thus adding more facets to it. Having slow parts, loud parts, fast parts, silent parts, dramatic parts, melancholic parts, and so on, would have opened up to a much more rememberable atmosphere.
However the director decides to be one dynamic, and the result is a 90 minute long opera/film, that gets pretty boring halfway through because there's nothing unexpected to it.
And even still, I was packed watching the movie and wanted to see it concluded, aware of the obvious faults. The conclusion, however, was the worst of all. The movie feels the unnecessary need to include an action scene, destroying the tension, and eventually ends way too late, in an effort to make up for the bad ending. This terribly performed effort was the nail in the coffin, for what could've been a great movie.