Superman's powers are never, and should never be considered a curse.
The Man of Steel's powers are a blessing for 2 very simple reasons:
Superman's powers are controllable.
Even Superman's Heat Vision is controllable; he's not like Cyclops "cursed" to always wear a ruby visor to keep his uncontrollable Heat Vision in check, and to keep him hurting others around him for the rest of his life.
Super Strength too; Superman seems fine being able to gauge between using it when he's mild mannered Clark Kent.
Only time his powers are probably not controllable is when Superman sleeps; maybe then you could consider that a semi "curse" or a super inconvenience, but then again Lois Lane may beg to differ about that with her "experience."
The notion that Superman's multitude of powers are a curse simply because he now lives a never ending life of protecting the world (universe) fom threats is just... balogney.
To steal Uncle Ben's "With Great Power comes Great Responsibility" - this rings true for anybody not just superheroes.
Superman is the global protector, that is his calling.
Just like when a person becomes a new Father or Mother, being a parent is now your calling. It's a blessing, never a curse to be able to protect those that need protection and to defend the weak.
People who do that are heroes. These people will always look to them, to you as a "hero", their hero.
Being able to make a difference in someone else's life for the good is and always be a blessing.
"How Captain America in AVENGERS gave the true meaning behind everything IRON MAN 3"
Kind of spoilerish, but if you've seen the movie, read on!
Iron Man 3 is Tony Stark's search for the answer to Captain America's question back in The Avengers: "Big man in a suit of armor. Take that away -- what are you?"
Tony had been holding onto his arc reactor chest piece because he thought it defined who he was.
In the end of IM3, with the help of the Extremis formula on Pepper, Tony could use it and also finally let his arc reactor go because he finally understood that Iron Man is the man who "built" the armor (The Mechanic) and not the armor that wears the man.
That similar meaning is also conveyed between Aldrich Killian and the real meaning behind The Mandarin. Killian was Tony, while The Mandarin was just his suit of armor.
"I am the Mandarin" was what Killian said to Tony during their final battle, which reverberated the last thing Tony said before the end. Because despite that Tony no longer has any Iron Man suits to wear, it didn't matter anymore because like Tony said in the end of the film even without the armor, "I... AM Iron Man".
P.S. On a different sidenote, Killian was the human version of The Mandarin's Fing Fang Foom complete with fire breath - how the roles have changed.