I just finished the single player and boy do I wish there were more times I could play as Ellie.
I haven't tried the "normal mode plus" but I assume that's just for your items and supplements getting carried over from the time you finished the game. Even better guess would be that everything is unlocked from the beginning just like God of War: Ascension.
What would be a pleasant surprise is if you could play Ellie from the very beginning.
That's how much I liked playing Ellie.
And let it be known that if you guys at Naughty Dog ever came out with some kind of DLC or Pay-Download for more Ellie action, I would gladly pay that price. Just make sure her levels are long and extended since I am paying :]