I like the split composition as well as the use of color and light, and the melancholy of the traveler, in images 8 and 9. But all in all, I think Stefano should work on gathering more elements in one frame and focusing more on the chore of his subject: a closer look at the couple in image 4 (and no window) may have made it a stronger image. In image 7, I think the image also suffered from “too much information”: no need for stairs on the left, and/or wall to the right. I think a closer look at the gondoliers would have made them much livelier. It is a great, happy street scene, but more focus would improve it a lot. As much as some pictures come quickly to you, and you want to take the picture as soon as it happens, in some instances you may want to take the time to turn around your subject to see which angle would make it more striking visually. So many photographers have so many different approaches to street photography - sometimes the beauty of a photograph lies in the immediacy of the scene it captures; sometimes it lies in the quiet that stems from its sheer timelessness.
Surely some of these images would become more interesting if I heard Stefano talk about them - I can sense that I am losing a lot of the original intention: for instance, what did he see in that scene (image 5) and what did he want to convey? Did Stefano try using black and white? What is it in color that attracts you most? If you did a book, what would be the connector between the pictures he would choose to include in it? Perhaps it would be a good thing to gather a few dozen of images - not only these, but others too - and try to order them in an album. It may be a good way to understand the nature of what you really enjoy looking at. Then focus more on the structures.
What matters to me as a viewer, and I believe what matters to Stefano as a photographer, is for him to take great pleasure in observing and capturing the daily lives of the people who surround him. He should therefor continue looking at crowds and individuals, in other cities, focusing on the colors, and on the lines. I would encourage him to spend as much time as possible taking as many photographs as possible. Shapes and patterns will just come into place naturally.