Yea, it is.
Some new characters were even confirmed.
Your favourite, Wind Walker Link, as a clone.
Most wanted Lucario, he's now our new Mewtwo.
R.O.B., noone wanted hm but he's pretty a good Idea, nice B-Moves also.
Ganondorf, now with a new Special Moveset.
Ness is back, yay...
Luigi, how could we exclude him? yea, he's in.
Falco, whic is in, will probably be a clone of Fox.
I wonder what Captain Falcon's Final Smash will be, because he's in.
The 2-Dimensional Mr Game and Watch is also in.
And who could not put Jiggly Puff in?
For those who want to know what charcacters are in:
Metaknight ( No, Kirby wont transform in him, as in SSF, he wont even be a clone)
Wario ( Pretty "manily")
Ike ( You might be wondering wtf he is)
Pokemon Trainer ( As three Pokemons , Ivysaur, Squirtle and Charizard)
Olimar ( from Pikmin, yea, he uses Pikmin)
Snake ( the Solid one hehe)
King Dedede ( the sadic oponent of Kirby)
Diddy Kong ( Dk's Partener)
Lucas ( As a Ness Clone)
Sonic ( The last, but not the worst)
More Information about Brawl at the Dojo.
No, they dont say about all characters, only the starting ones.