I had time to test it, here are some things you can improve:
1- Dynamic range. In night mode the lights are very pretty, but you need to increase ambient, because it's no fun when you can't see half the map. My screen is adjusted well, in fact I use a hardware calibrator, so the problem definitely isn't on my end. In day mode the light is equally wonderful
2a- If you want to stick with the keyboard-and-mouse control, then we need to be able to control the character without moving our left hand from the keyboard. Currently we need to do that to hit enter to leave/enter a car. I would also like to be able to control the character using the arrow keys (or any other alternative such as W S A D) while using the mouse for aiming.
2b- I would prefer a keyboard-only control, not only because that's the way it is in GTA2, but also because of the skill such control requires and helps create. If someone had told me I could run around in GTA2 and then to snipe another player at the edge of the screen using a rocket launcher (none in your game?) while turning around, I wouldn't have believed him. Now I don't need to believe it, because I can do it. I don't think a keyboard-and-mouse control can get anywhere near that. I suggest you let the player choose how he wants to be able to control his character, whether keyboard-only, or keyboard-and-mouse, adjustable in your options panel. If you do implement this, remember to disable weapon shot spread - weapons should be 100% accurate (99% at least, just to keep the graphics from being identical) for keyboard-only mode, otherwise the skill I wrote about above won't apply.
3- The game should not hog all key strokes - it should allow one to use alt+tab and other keyboard shortcuts (kde, gnome, windows, etc, plenty of different possible keyboard shortcuts there!)
4- Clipping. Too many things are solid. While realistic, they make car chaces no fun, or even walking.
5- Weapon boundaries. Although there's a large blue light around weapons, we need to go right across the middle of them to pick them up. It would be nicer if just going over the blue light was enough to pick a weapon up.
6- Our character seems to only be able to walk. No running = no fun (eh, DMA?)
7- Cars are anemic. The game would be more fun if reversing didn't take so long.
8- Car auto-alignment with the road doesn't always work well. It seems that when I drive fast the game tries to align my car with the road, but it often fails and only aligns me partly, I still drive off the road at a small angle. e.g. If the alignment would require a 20° turn, the game seems to align me 18° and I'm still left driving off the road at 2°.