New Super Mario Bros. 2 has a lot going for it, the level designs are great, the powerups from the original New Super Mario Bros. (namely the mini and mega mushrooms) along with the revival of the raccoon tail make for fun time, and the focus on coin gathering (including having a coin themed power up) only adds to the amusement.
However New Super Mario Bros. 2 has two small failings. 1) I have played the same game before... it felt almost exactly like the first New Super Mario Bros. on the DS and it doesn't help that I just played New Super Mario Bros. U on my Wii U (although NSMB is more similar). 2) It's too easy. Granted 2D Marios aren't known for being overly difficult but NSMBU at least had some challenge to it. Here I was able to get from start to beating bowser in less than 3 hours of playtime (mainly because I didn't have to retry more than a handful of levels).
I gave the game an 8 because I couldn't give it a 7.5 but didn't feel it deserved a 7.