Anyone who is around as old as I am and was around for when Super Mario World was released on the Super Nintendo (Famicom) can relate to how incredible that game was. The ability to select your own path through the world and also to choose to skip entire areas via secret level was pretty epic. Therefore, when I saw that Super Mario Bros 2 on 3DS was employing the same game mechanics I was really excited.
Once you enter each of the "worlds" you return to a slightly tweaked (and of course far better graphics) version of the original gameplay that we experienced back in the 90's. The major powerups are the fireflower (enables throwing fireballs) and also the tail (can hold jumps longer, whip enemies with your tail, and obtain flight after a long sprint) and these are always welcome.
My favorite levels have always been the haunted houses and nearly every "world" has at least one of these on them. After all these years I still find the ghosts that are too scared to chase you if you look at them to be incredibly cute.
I don't know if this game was designed specifically for children, but i was able to finish this game in about 6 hours without really even devoting much attention to it. I also finished the game with over 50 "lives" in the bank. It is incredibly easy. There are optional worlds that you can unlock by getting big coins (not the correct term) that are placed in challenging areas, 3 in each world. Most of these unlockable areas simply offer upgrades given to you by Toad and this kind of makes it a bit pointless since these powerups are quite easily obtained in the regular levels.
Overall, I would say this game is good because it is graphically impressive and the levels are lovely and fun. I would have appreciated a bit more challenge since I honestly can't imagine anyone over the age of 5 being incapable of winning this. I'm not saying that I want games to be impossible because those games annoy me even more. However, being able to finish a game by just playing it a few hours seem to be going in the wrong direction for me.