Not really, Superman is powerful, but his various incarnations run the power and ability gamut so widely you would have to ask, "which Superman?". Are we talking about old action comics superman who was powerful, but couldn't even fly, and wasn't anywhere near city destroying levels? Are we talking about golden age Superman, whose powers consisted of pretty much anything you could stick the word super in front of, where we got things like super ventriloquism and super knitting powers (yes those were real super powers that he calls out by name)? Are we talking about the Silver age Superman, a god among mortals, but still regularly got his ass handed to him by mid to high level magic users? Or are we talking about modern Superman, whose lost a lot of his power, and in the new 52 books, gets taken out by a Wonder woman B team villain like cheetah (again this actually happened in the new Justice league books)?
Actually, you know what? Scratch all of that, because Mary Sue is a stupid overused term that people like to tack on to any powerful character they don't like. The term is basically meaningless at this point, people throw it around as a criticism without actually explaining why they think the character is bad, just "he/she's a Mary sue" and we are supposed to just accept that as scathing condemnation.
With Superman it's a meaningless label, he's written so differently by so many authors, that it's impossible to apply a vague simplistic label to him like that. Even in the context of the DC universe, Superman regularly gets smacked down or defeated by a whole bevy of cosmic powers and magic users. Calling him a Mary Sue tells us nothing, there are plenty of things wrong with various Superman series that have nothing to do with how powerful the guy is.
There's a reason that the term Mary Sue got started in fanfiction. It was to originally refer to a wish fulfillment character that sidelined the story away from the canon characters, and warped the established canon to make the author's own original character look more special. If we start extrapolating that out to canon and professional works, then the term loses a lot of its meaning and just becomes a synonym for whatever someone doesn't like about a character. People will call Mary Sue because a character dared to fall in love with the protagonist, or just because they are powerful to some extent, even if they regularly fight villains and challenges just as powerful.
Leave the word Mary Sue in fanfiction where it belongs, there are plenty of critiques you can make about Superman without dragging up a stupid term that has no official definition. It just poisons the arguement and changes it from. "is this a good/entertaining character?" to "Is this character a Mary Sue? What is a Mary Sue?" basically once the word Mary Sue gets used, the entire conversation derails, because everybody is using their own definition of what exactly a Mary Sue is.