That's way too harsh; NSMB games get far more flak than they deserve. These games unfortunately bear the burden of comparison to some of the greatest ever, so they fail to live up to extremely lofty expectations. In the realm of all 2D platformers, they are well above average.
i think they're average at best. the art is 90's shareware bad, music forgettable or annoying and the gameplay is more 3D mario in a 2D perspective than old mario. the clasic 2D games felt amazing which is why they still play well today, the new mario series plays like slop in comparison.