I like it for the most part, but a few things could use more attention. I think you should spend more time on it and really make it look nice.
My main concern here is the rivulet that runs throughout the map. For the most part, it's pretty blocky and looks totally unnatural. It also ends abruptly. I think you should incorporate a large canal off to the side which is inaccessible to players and have the rivulet drain off in to it. As for detailing it, you should try and use displacements to give the ledges and the joints in the stream a more rounded look. You can also make the "rushing water" look smoother at joints (and seamless) using displacements. You can set displacements to not collide with anything so players and phyiscs objects won't collide with it and look awkward. It would take a lot of work, but it would totally be worth it. Your map would just look so much better in the end.
Other areas that could use attention are:
The ground in screen shot #4. It looks strange to be honest. You might be better off sticking with just cobble stones then adding clutter props near the walls and whatnot to keep it from looking like a plain, flat floor.
The raised "grassy" areas with the boarders which have trees and other foliage growing in them are blocky and clumsy looking. You should attempt to increase the detail by using more brushes. You could top the boarders off with a "hat" brush of sorts, so it looks more like a "fat T" rather than a simple rectangular prism (get the idea?).
The "bases" to some of the trees simply look like displacements that recede in to the ground, which creates sharp, ugly seams. For the bases to trees in grassy areas, you could use blend textures, and raise or lower the displacements a little bit at the base of the tree then alpha paint the bump/depression. This would look much nicer.
As for trees that are on the sidewalks (on concrete), I would try and do something like this:
Notice the metal base. There's actually a "hole" of sorts in the sidewalk which contains soil for the tree, and there's a metal grate over the soil base to keep people from stepping in it. It has a hole in the center for the tree trunk. Finding a suitable grate texture might be difficult, however. Up to you though. Alternatively, you could look at the models for de_corse. There's a "tree ring" model that would also work well as a base.
Another major thing you should look in to is the 3D skybox. The buildings you used seem rather inconsistent to the setting. You have a mix of modern city buildings and that big cheap apartment building, all of which don't really fit in with the actual map. You should try creating more buildings like the ones in the playable area. Look at cs_italy and de_inferno for references. It seems like you used assets from one or the other (or both).
Cool idea for a map though. I hope you plan on working on it some more. It could turn out to be a really cool map.
