Physics:Characters are lighter in general,and they have better jumping ability.

Items:The new ones are fun,but some are kind of unfair...*CoughDragoonCough*

Assists:I personally don't like them,but I will say that they liven up the fights.

SE:Fun,though some of the levels are sadistic on higher difficulties,And Bosses can kill quickly if you're not quick on the buttons.The trophy stand idea gives more replay value to it,and enemies are diverse.

Characters:All of them are equally usable,as is the (Casual play) Smash Bros. quota.My Favorites out of the new ones are Wolf,Lucario,Wario,Metaknight,R.O.B.,Olimar and DDD.

Stages:I don't like many of the stages,though they are diverse.My favorites are Norfair,Spear Pillar,Mario Circuit,Delfino plaza and The summit.

Music:Hit and miss,I like the orchestrated arrangements but the retro sounding ones are just awful to me.:/

That is my unbiased asessment so far.I'll write the review once I finish everything.