Ribeira de Gaia e Serra do Pilar.

I would like very much to see yor opinions about this picture... what

is wrong, what is right...

I think you have the elements of a good photo here, but they haven't come together. Everything is a bit cluttered, and we don't get a clear picture of anything. For instance we have somewhat less than half the bridge, and a bit of the town.

Try changing the viewpoint so that the various elements stand in a better juxtaposition. Eg try a shot along the length of the bridge, or from close to one side of it, but getting it all in. It looks like you could make some very spectacular pictures with a wide-angle lens.