I'm the worst person to ask for detailed feedback, I go on and on forever and sound like a jerk.
It reads like an ice cream van/truck, so clearly you're doing quite a bit of things right :]
The one structural nitpick I have about the van is those wheels look too small, it looks like it's missing tires.
I think the composition is dull. You have the vehicle right in the middle (closer to the "front" even), giving it no breathing room in front of it. Having more space in front of it would allow the viewer to anticipate the motion a bit more, making the whole piece feel more dynamic. With more space around the truck, you could add more life to the animation by having it shift forward and backward a little, as if it's changing speed slightly (as cars/trucks often do when they're not on cruise control). I'm not sure if I'm imagining it, but it looks like you already have a speed change in the animation. That would read much better if the background moved at a constant pace, and the position of the truck changed within the frame to indicate speed.
The background being largely dullish warm colours works very well, it looks nice and doesn't clash with the ice cream truck, which has more contrast and different hues. However, the "DUCK" part of the graffiti does clash a bit. I would change the white in those letters to the light yellow you have for the sidewalk, so it's not as contrasty.
Background nitpick: The bricks are all perfectly aligned in rows and columns. This is structurally unsound and looks weird since most people are used to functional brick walls that have each brick centered on the joint between the two bricks under it.
The shadow on the pavement under the van is much lighter than the shadow on the van cast by the green awning, which is odd since the awning probably lets more light through, and there's more reflected light that could get in where those shadows are, compared to the shadow on the pavement. I think this is one of those rare cases where LESS contrast would look better.
The ice cream cone makes the van look flat, like a cutout, because it leaks over it. To show that the ice cream spreads out horizontally before leaking over the edge, have some thickness to the ooze, and have it spread further backwards and forwards.
The chrome looks nice, but you've got the stereotypical "desert and blue sky" reflection going on, even though your scene seems to be in a city. Have the chrome reflect the setting, it'll make the piece look more unified instead of standing out so much. You could use this to add some animation to those hub caps as the scenery they're reflecting changes as the vehicle drives past.
Thank you for cnc I would take it in the next time. I thought about that but I've spent almost all day on this. This is my first big animation ever.
What do you think about anything else. Colors, proportions, composition etc..?
I think this piece would benefit from some indication of motion on the wheels. Realistically there'd barely be any, but it just doesn't read well. Some rapid jittering of the hubcaps might help, or some grey variation on the tires that spins. Because there's no animation on the wheels, it looks like it's sliding.
Made some rework