Why spidey is having dificulties in the trailer ?

[marreco]

It is to false in the trailer spidey is like he'd never had a web swing

and he is like having difficulties swinging in the air
but if he realy has super strengh he would make it easy like in the comics and in cartoon

[cathoderey]

He's not having difficulties with his web. He can't propel himself by sheer will alone. He has to gain momentum and swing himself like a pendulum; releasing his last web at different points to move forward, upward or downward. Haven't you ever been on a swingset before? You need to get pushed to get moving. Since no one obviously pushes him, he has to generate forward momentum by acrobatics. In comics, the artists chos the best pose and freeze him in it for the sake of framing the scene. They don't have to do that in the movie.
I think it's a great effect and enhances the credibility.