There are a bunch of small differences with the backgrounds, but most of the major ones have been covered, or at least have the same feel as the originals. I asked about this before and he said it wouldn't be feasible to give every level a different background.
Maybe release some of your development information/sourcecode for your work, and let other people expand on your work? MIght be useful for making hacks for Mario 2 Lost Levels too to add in the new content.
The other problem is that technically there's no "exact" colors on the NES. It depends on which TV or emulator/palette you use. So it's not possible to exactly copy colors how they are on the X1. The previous attempt someone made in one of the old patches looked pretty bad
Also I want to say I am extremely thankful to frantik for all the work he's done on this hack and the effort he put into remaking the backgrounds and other features as close as possible
Ya, and without using some real trickery and special chip/advanced mapper functions, it would be impossible to get dithered colors on the screen like on the original version. It simply uses too many colors in a different way than NES handles colors... I tried to leave links that explained NES method earlier...
Ya there was one patch that tried to do 'similar' look, but if you look closely it dropped a lot of colors.. For example it uses magenta for all the stone work, when it should be bright (red) (NES doesn't have equivalent color, there is a slightly brighter red color, but not sure how it would look), and magenta does make the trees in 4-3 look more like the trees in 4-3 of X1, however, then all the blocks look magenta too when they should be red to show the difference in terrain. But you'll notice that the dithering is missing from the trees which defeats the whole 'wanting to have everything dithered' look.https://arstechnica.com/gaming/2013/07/time-to-feel-old-inside-the-nes-on-its-30th-birthday/2/
Also as I mentioned NES had limits.. to only 3 colors per tile, at a time and only four color combinations at a time... The X1 looks like it could have quite a few more tile color options (seemed like its over 6-8 color tile sets, roughly 3-4 color per tile) but could handle only 8 colors on screen at a time....