I think much of the complaints stem from Superman movies not being critically acclaimed blockbusters like (many) Batman and Marvel movies. And the expectation is that since Superman was the "first" and "best" superhero that he ought to be the best in the movies.
But I am in the minority- I really don't care about 2 hour movies and have no idea why people bashed Superman Returns. (I found Superman & Lois to be such a pleasant surprise.)
And, another unpopular opinion, but Alan Moore's Supreme did Superman better than DC has been doing him since CRISIS.
It is so freaking stupid that a virtually immortal character gets rebooted every decade or so, and has a bunch of alternate characters running around instead of just being the same character from 1938, who remembers everything. (All-Star got it right.)
And now with the copyright going up soon, things are probably about to get worse for the Man of Steel.
It doesn't matter how other companies handle Superman pastiches.
Although I do not believe Superman can't be written well in modern times, apparently Hollywood and people who don't read comics think so. It's the same tried old criticism- he's too powerful and he's a boyscott. All stems from the freaking Silver Age and Christopher Reeve. DC has deconstructed that so many times but the mainstream never got the memo. Just pick up any post-Crisis comic book and Superman is not portrayed as being 1961 Superboy. And people forget about the successful TV shows and cartoons where Superman comes off great.