First impression was terrible actually, but not because of the simulation itself but because of the pesky installation and online activation procedures. Beyond that however, I have to say this is a neat little sim with much potential to become so much more (if allowed).
It's perhaps one of the most boring and perhaps unrewarding in the long run, but it pulls of what it's designed to do. I checked it out simply because I'm a fan of realism and because I have a sturdy FF wheel and a TrackIR device. I can't imagine how anyone could use this app properly without one actually.
From a serious sim racing enthusiasts perspective, this game is not a vehicle simulation. It lacks a proper tire & suspension model etc. The reactor physics engine is not suitable for simulating car behavior but more suited to calculate props bouncing around in FPS games. City Car Driving can however be regarded as a "city driving simulation" and it could even be one of the better available for home entertainment. If City Car Driving had a more complete package with interesting and challenging "missions", for example transportation, delivery missions or racing (illegal), perhaps with cops

then City Car Driving would end up being so much more then a simple learning tool for novices.
The graphics engine is potent enough to deliver a good game oriented experience. Imagine being able to cruise around and randomly challenge AI cars to race (maybe honking the horn) and then you simply choose the destination on the GPS and line up

Such a feature would be fairly easy to implement and it would result in endless of fun! It would require some new AI code for the racing part however. Also, a simple form of damage model would be a good thing, just enough to keep you from driving too dirty. It could be some type of engine status, loosing power at 50% damage and terminal damage at 100%.
Just a few thoughts. I know City Car Driving can't compete with mainstream racing games but it's design is original enough to stick out and if it where more mission oriented it could gain renown for being the most fun and "realistic" driving challenge sim / game around.
Cheers.