Invisible Man on the other hand focuses massively on irony and environment/setting details. However in my opinion it falls short instead on the protagonist. While I don't think the narrator is undeveloped, find him a bit boring. In the beginning of the novel, he's clearly not meant to be very relatable. He's submissive, naive, and almost without any self-respect. He doesn't really have any striking ideals or personality aspects that I find interesting. Later he breaks out of this character somewhat, becoming a great deal more skeptical and aggressive. However these personality aspects are really only noticeable because of the contrast to his old character. As far as I'm concerned he's become an average, educated young man, still without any particular ideals or goals other than to be vaguely successful.
Now one could make the argument that Ellison's huge environmental and ironic depth makes up for the lacking protagonist, and it does to some extent, and while the constant ironies give a lot of potential for analysis, for me it gets a little old. The plot is a bit too predictable, and you can hardly read a page without being thrown with some irony (or what might be irony). If you combine that with the often predictable narrator, the novel often seems fairly unimaginative. While the prologue gets us wondering how the narrator develops, I wish it didn't exist at times, because the reader not only knows where the narrator will end up (irrelevant and "invisible"), but we also know his final psychological result, which I don't enjoy knowing.
Please keep in mind that I'm not done with the novel yet, and I am quite biased towards Native Son. I just think Invisible Man is an acquired taste that I don't quite have.