Yeah... this might've been a mistake.
Oh well, I just inputted the codes and got meself all four bonus characters, the costumes and the abilities, which I'll be taking all the way through to the end of the game.
Hawkeye: All his cotumes are decent, but I specially liked the 'Street Clothes', the one I'm using. His skills are fun to use.
Ronin: All her costumes are fantastic, but I'm going with the second one since I loved the abilities, and her skills are top-notch, they look devastating and feel fun to use.
Captain Marvel: I didn't care for his appearance, any of them, so I went with the default look. His abilities are alright but nothing caught my eye.
Black Widow: I actually thought her default appearance was the Winter Soldier('What? A fifth bonus character?! Oh, it's Black Widow....'). Can't say I care about the character either, but I went with the Yelena costumes since it struck my fancy the most. Her skillset is alright, but I'm particularly fond of her first skill, since it feels powerful.
All in all, as much as I'm liking Roning... the rest of the cast are alright, but nothing to write home about. Even if you love the game you can do without these extra characters. Or you could download the PC mods and add Ronin to your roster.