Oh, this didn’t happened here, personality stayed same, maybe a small change to Mickey, more of leader personality than classic always-smiling Mickey Mouse.
This game doesn’t have friendship system which DH:BM have, but some missions involve dialogues between 2 characters (some kind of building relationship):
Jack Sparrow - Merida
Jack Sparrow - Scrooge*
Sulley - Oogie
Elsa* - Genie
*unplayable, yet
This doesn’t give anything it’s just part of the game plot.
Each mission have few dialogues, so there’s story and plot 
There’s Discord channel for this game:
Inside you can find link to official reddit.
On discord is spoilers channel which have some upcoming characters 
As for me Mirrorverse is way better than DSA and it’s real competition for DH, hallelujah, finally!
Mirrorverse, other than any other game offer unique look at Disney’s characters.
As for now game have good balance, but as always in each game some characters offer a bit more 
and yes, it’s F2P friendly.