Scorcese is a bit overrated, I think, even though I enjoy most of his films.
Not one of his films has really struck me as being a masterpiece, and yes I have seen Taxi Driver and Raging Bull.
I must admit, however, to possible bias, as I usually gravitate more towards films with sympathetic characters, or at least individuals with sympathetic characteristics. Note that this does not necessarily mean that I can relate to those characters - one of my favorite films is Fellini's Nights of Cabiria, and I have never yet made acquaintanceship with an Italian prostitute.
So it's probably mostly my personal bias against his type of films. But I also would take issue with the argument that he has great "technique" as a director. Many of his films are sloppy and lacking in remarkable scenes.