The wheels were the biggest problem. Bigger ones were too big, smaller ones used in town cars were too... townish, and technic chain threads somehow didn't look good here. Round brick 2x2 wheels are ok, but they don't have any grip so no rotating even on carpet :D
For something so new to you, I think you did a good job! The color actually looks good, and everything is either smoothed out and/or rounded. I like your use of the pivoting bricks on the wheels, it's a nice look. The miniturret at the top, as well.
Very nice job!