Yeah, the new Siren (Maya) has the phaselock (aka cool time dilation field) ability instead of phasewalk and the Assassin gets the stealth.
I see phaselock as a variant of Mordecai's Bloodwing... it slows down the target like one of Bloodwing's abilities.
The Assassin's stealth attack is phasewalk's stealth and a replacement for Brick's melee beserker skill since Zero is the only one with an ability that has a melee attack.
The new classes will be interesting. Not sure which ones I want to play as the most.