Not as good as its predecessors.
NOTE: This is a review based on the 3DS version not WiiU.
As a big fan of the franchise I must say that this is a welcomed sequel and great game overrall, except that the 3DS version isn't the best in the franchise nor is the WiiU version (which I only played once at a friends). So I am going to review this game while also thinking about it's predecessors.
Story - Unfortunately, non existent. I really enjoyed the Brawl story even though no one talked, I loved this humour in it which is a shame to have no story in this game. The only thing that comes close is the classic... er... Classic Mode as well as Smash Run which are for the most fun pretty fun... for about 10 minutes. I just find it hard to keep playing this game when you get no rewards, you can go for the challenges but you need a friend to do the street pass thing with you which I don't have any friends with a N3DS. They also have modes like Multi-Man Smash, Target Blast and Home-Run Contest that can be fun for a bit too. There is also All-Star mode which is unlocked automatically unlike in Melee where you would have to unlock every character. They seem to be missing a lot of content from the previous games which sort of sucks.
Characters - Well... I can talk about this forever but with a whole range of selectable characters you just have to pick one and hope for the best. I am starting to get good with Pac-Man and Mario, but I love using Little Mac he is just too much fun to play. Each character has their own set of moves plus a final smash from hitting the smash ball. The only problem with these characters is that they are WAY TO EASY TO GET. I mean to get a character is Melee you would have to plug in a second controller, go into smash match and leave your gamecube on for 20 HOURS, then when you wake up and notice the challenger approaching then you immediatly go nuts and defeat him. In Sm4sh however I unlocked every character in about 2 hours which didn't feel all that rewarding like it used to. Anyways that is my only complaint.
Gameplay - It feels like a smash game all right, the controls are very responsive and runs at a great and steady frame rate. The only servers however are quite trash when playing with 4 people which is unfortunate but I can play 1v1 with no problems. People sometimes complain that its slower than Melee, and to that I say... your right, if you like a fast game than go for it, this game plays fine. Anyways in this game it runs like the previous titles: you keep hitting the character and try to get their percentage up really high so then when you get it high enough you give them a nice strong smash to send them flying! Unless you are facing against the Master or Crazy hand (and another boss which I will keep a secret) which they use HP so you try to get it to zero. Also in the stages there are items which you can use to give you a boost in battle whether it would be releasing Pokemon, gaining health from a Zelda fairy, or a baseball bat that has 1 hit KO's these can help you in battle.
Graphics - With the 3D on it looks really great, I like how the stages look like they are in the screen, like they don't pop out at all, but they look like the stage is in the screen, its a really weird and cool effect. Everything looks great but the WiiU does look a lot better (obviously) but I would rather have a smooth frame rate then over textures characters.
Controls - The controls are great for jumping and hitting, but hitting the L and R buttons is really card during combat and its really uncomfortable. You will have to take turns putting you index fingers on the back of the ds then when you need to dodge, block, or grab then put your index fingers on the L and R buttons and do what you need to do.
Sound/Music - Holy crap is this soundtrack wonderful. The intro music is awesome, the remixes of nintendo game songs are awesome, and the sound effects for every single thing you do it GREAT! My favourite part about this game
Final words - I recommend this game to anyone who likes fast-paced fighting games.
Story - 2/5
Characters - 4/5
Gameplay - 4/5
Graphics - 4/5
Sound/Music 5/5
Controls 4/5
Final Mark 4/5 stars
I don't find as good as its predecessors (except Smash 64 of course), but it is still a great game and a good time waster when you have nothing to do.