Bobobot was the comic relief in the Mazinger Z series. This robot actually had facial expressions that changed according to the pilot, Bobo’s mood. This image, I think, makes him look a bit expressionless and almost zombie-like, in contrast with the cartoon’s very human-like expressions. It’s so difficult to capture emotion and expression and personality in just a few pixels, which is why I’ve refrained from trying to draw them.
Generally, I feel that it’s better to go abstract and just convey the impression of the overall person, rather than try to convey facial expressions at the resolutions I’ve been dealing with. This serves as a good example of why. It would take a great deal of fine tuning and high-resolution finesse to get the nuance in the expression just right. If it’s critical, it is worth it, but it is a lot of extra work, and takes a true artist to pull off well.