I love Namor. I don't even think it is that hard to write good Namor. Stern, Johns, Bendis, Hickman, Fraction all gave us some sweet Namor moments, based around the simplicity of the character. I don't mean that in any bad way. Throw him into a team of Avengers that has no other flyers and I think he would work very well. Ever notice how hard it is to draw a convincing Namor? Maleev made him into a rat man. Most artists flatted his head too much for my liking. I'm better with writers than artists, but i think it was Deodato that nailed it.
Honestly, I think Maleev is one of the few to really have trouble with Namor because he was purposely trying to go against the mold. Namor's "mold" is really one of the easier molds-- he's positively Vitruvian.
I do sometimes wonder about the head. Look back to the Golden Age, and his head is damned near triangular (almost as much as Pyramid Head). Is it wrong to make it "too flat?" Or have artists been wrong in making him too human? Is head shape one of his undisclosed powers? Is he really just a humanoid starfish?