My comments...
#1 - Horizon seems slightly tilted to the right. Am I right in say that it was shot with the wide angle lens? Getting the balance right can be quite a task when shooting with the wide angle so its down to trial 7 error to get it right but constantly check the viewfinder to make sure. You might also need to stop down a few more stops as I noticed a bit of vignetting at the top left and right corners.
#2 - Too much uninteresting sky on the left and abrupt cropping of the buildings on the right... composition not balanced.
#3 - Horizon not level, tilted to the right. Good point for reference in such a situation would be the bridge across the river/water expand. Another thing is that the abrupt truncation of the walkway on the right is spoiling the effect. Ideally, the diagonal line of the silver railings should have continued and ended at the bottom right corner.
#4 - Horizon not level, severely tilted to the right... left side of the image very much higher than the right. Colour is nice though.
just my 2-cents worth...