There's no question that a fair number of the songs sounds fairly similar in nature. But quite frankly, I find that to be the case with most artists, critically-acclaimed or not.
That Sufjan Stevens album that all the critics are going gaga over ("Carrie and Lowell"), for instance, feels like one long song to me.
Which is why I've always favoured musical diversity over "cohesiveness". The individual tracks leave more of an imprint, even if they don't flow as "organically" into one another.