I adore the Super Mario Bros. 1 SMAS NES-ized hack from hiro1112 since I wasn't crazy about how the original game looked, it's mostly a big improvement imo. I have one small nitpick and one large one that is my main reason for coming here. The small nitpick is the trees in world 1-3. They've got a blurry texture. That's it.
Now for the main reason i'm here, this isn't an issue with hiro1112's hack as it is an issue I have with the original Super Mario All-Stars. The hack didn't fix one of the biggest problems I had with the original version that makes SMB1 look not quite right. I actually made a visual. Take a look at this.
This is how the hack looks normally... well, it's a mock-up since those enemies and Bowser normally don't appear there, but if they did, this would be how they looked. Does Mario and that Mushroom kind of look like they don't belong there? They got those thick black outlines like they were meant to be from a different game, and that's always bugged me about even the original Super Mario All-Stars.
Now take a look at this:
Doesn't Mario look more like he belongs here now? The original NES game didn't have any bold outlines on their sprites, and the SNES remake sort of emulated that somewhat. They have outlines but instead of being black, they're just dark colors that make it look more like shading.
But wait, that still just looks kind of like they slapped the Super Mario Bros. 3 sprite in SMB1 huh? Let's fix Mario's posture.
There we go, now THAT's a faithful remake. But as the title of this thread implies I've got the idea, but not the skill ( or the time, frankly )
EDIT: I've been dabbling in actual hacking and managed to fix the ugly bowser and orange yoshi arm in Super Mario World, and I was feeling like pretty hot shit, so I wanted to actually attempt this, and reverse Mario and Luigi's overall colors in SMB2 and 3 as well, and I could not even begin to know what I was doing when I tried, I don't know how you more talented folks do this, but you've got my respect.