Nonsense. Shostakovich knew people who were lost in the 900 Days, and he would not have dedicated to the people of his city any piece which he 'didn't even like himself'.
I hardly think that the disdainful term 'overhyped' gets any purchase on this piece. It is a unique achievement in the arts, and is rightly a symbol of the activities of culture enduring in the face of barbarous violence.
If anything, it's one of his most underrated symphonies, because of the attitude. I personally love this piece, hell, it's in my top three of Shostakovich's symphonies. 1 Being the mighty 10, and the 2nd and 3rd are 5th and 7th, interchangeably. I personally love the march in the first movement, I adore the 3rd movement, and the 4th is one of the best finale's in music.
I mean, it's my own personal opinion, but it's far from trash. Very, VERY far from trash