Thanks four your comments. I agree there is many errors pixel art technic talking. 

The strange perspective was mostly done on purpose to give un unrealistic, strange feeling.

There is many light source shading errors. The main reason is that i pixed most of the person before creating the scene, and then changed it it without modifying persons. Some parts were rushed at the end before one deadline.

Many errors such as the foot like on the car roof should have been corrected to, you're right.  Many pillow shading... I'm trying to correct my pixel art errors from one gfx to another.

I've read previous days many tutorials to avoid such errors. Need to practice more & more.

 The idea itself is cool, but there are some serious flaws that make it rather bad:

1. The shading's pretty bad. It's borderline pillow shading. Take the sidewalk, for example. Does each border stone have a light source at the same place? Or the car: Does each door have a light source at the same place? The answer is nope.

2. There're some serious detailing problems. The bald gunman on the left, for example, has one foot on the sidewalk and the other on the car's roof. That's quite impossible to do... The car's hubcaps are rather badly detailed, too.

3. Some really freaky shapes. I'm talking 'bout the speech bubbles, obviously, the poster, obviously, and how the left sidewalk ramp up to the corner and the right sidewalk ramp down.

 Nice job. I like complicated scenese that give you lots to look at.

Its interesting, but theres a few things holding it back.  Some bad pixel techniques like banding is making it look a little blurry, and kind of grainy in some places.

The strange perspective, and unrealistic sense of scale gives it a kind of flat and modernist look.  Though in that case, you need to give more attention to color distribution, balance, and composition on the formal level.