My wife is a big fan so we picked it up on day one. I've not played the original very much so I'll just ask her and convey it here.
She said she's excited to be able to finally play it but really dislikes the the format changes (aesthetically). Also she doesnt like how the competitive mode has changed. Now its just one game win or lose, instead of best of three. Another odd thing is that it does not track your scores in (local) MP--not sure about SP though. Her and her family loved too site down and play local MP all the time.
She said that as an avid fan of the original, shes unsure as to why they made all these changes to this mario game but not to the other Mario or Super-Mario games. She equates it sorta to what Lucas to did with the SE SW movies at this point, but granted we still need to check out te MP and SP. She says to only pick it up if you cannot play the original--but that might change with playing the other modes? We'll write more thoughts later?