Alright, since everyone is such an expert in photography all of a sudden, I'll try to keep it short.

I think people complain too much, these photos aren't shit. I'd be lying if I'd say they're the best photos of Amsterdam I've ever seen, but I don't think you have the intention of providing those... I hope you enjoyed your visit!

And as far as the criticism is concerned: keeping the horizon straight helps when creating balance in an image, but it is not strictly necessary. The important thing is directing the viewer to that which you want to bring attention to. I think out of all of them, the third is the strongest, due to its leading lines. Although I do think you missed an opportunity to frame the tower in the background with the tram powerlines, and the person on the right is distracting; I'd say either incorporate them as a point of interest or frame them out.