Minus the "PlayerL100" across the top, I'd actually disagree, the tight spacing and consistent character size really gives off a nostalgic NES vibe, which I presume was the intention here. As for the art itself, I feel like the Overworld sprite may be a bit too small (could be just me though), but still really well made, I'd try adding the darker blue to the helmet as well to provide some shading like on the rest of the armor, but I didn't bother to check each 8x8 tile to see if that'd break NES limitations or not.
The portrait, on the other hand, I really love! I don't see much wrong with it, and it looks really nice especially for the era being emulated here. If I had to say something to be improved, I'd say it'd be the shading on the body. Humorously the opposite of the overworld sprite, the helmet in the profile has some really nice shading, but the rest is just a flat blue. However, given the NES style, I'd say it's an optional thing, and looks just fine as is, already appearing to be something you'd actually see in a mid to late era NES game!