It's supposed to be satire.

nice avater

Thanks, edited it myself. That's why the paint job is so terrible.

the paint job has that "its bad but that makes it good" feel.

What makes it retarded for you?
Is it the premise? The characters? The mood of the manga/anime?
Here's my two cents:
What I like in OPM is how mundane the character is. A super powerful man that has the power to punch reality to submission, yet he is a hero only because he wants to be.
The story is good in the sense that it makes characters around the protagonist evolve.
The protagonist has been given his character evolution right off the bat, so it's not that interesting to follow what Saitama does. What is interesting, is seeing how others react to Saitama, and how others basically act around Saitama. Basically, what I mean is, that OPM is a series about an insanely powerful guy, who causes others around him to strive to get better and change their perspective of the world, and themselves. It's an interesting and fresh concept to storytelling, which makes me interested in it.

what really ruins it IS the main character, really everything about him is just annoying (plus the superman OP level is just dumb)

Him being supermanly strong is the joke. Also what else do you mean with everything? His attitude? Well he just doesn't give a crap about anything. He wanted to be a super hero, but now he's become so strong that nothing is a challenge to him, so why even bother.

Also, the anime has sick animation.

yes its the joke but the joke isnt funny

The premise is retarded, but the execution is surprisingly good which makes it enjoyable, and if you forget about the retarded premise then it's great.

really? because i watched a few episodes and lost brain cells, its really annoying