Personally, I find Kat and Emmett to be great examples of what everyone in the game should feel like. You can tell they were "late" characters to the game, rather than some of the first made, in that they emphasize the strengths and weaknesses of the creators very well.
Kat has a branch in her base combo chain (all the best seem to), unique movement options, moves that can truly help out her teammates (Grav Repulse and Attract are great for her and for opening up enemies to others kills and supers), and Supers that actually have Solid setups and uses, without being over-powered, or under cooked. For all the burst combos she has, most of them require her to start the chain on the ground, which is more and more unlikely as people learn that aerial combat makes it harder to die VS many of the characters in this game.
All of her confirms take some kind of setup or commitment too, which makes her a prime target to kill during those times. It's her balancing factor; She can't flail about and protect herself as well as Raiden, and her lvl 1 is pretty risky in the simple fact that it roots her in place for a "long" time, on hit or whiff.
Her throws leading to combos is also great, and the fact that none of them lead to threshold combos (since they force aerial state) is well done. Steal some of the enemies AP, earn some for yourself... well balanced. For all their utility, they also have kinda crappy activation range, and once again, she's fairly punishable if she misses.
Oh, and I'm glad they choose the Spy outfit for her default alt, personally. It's more unique (even if Kat's is nice, I tired of the "schoolgirl is always the bonus costume!" mentality of Japanese games), and I like the clash of Light-hearted Kat with a costume that seems all serious and professional. Plus is also lightly references Yunica/Sea Wasp, while her other outfits have no real ties to any other big-deal characters.
I'm glad we'll get the Spy outfit eventually, moreso because it's like the "supervillan" to her normal "superhero" personaliy, than anything else.
I haven't played Emmett, but I've fought along side one the entire time I've been learning Kat, and I have to say, I really enjoy what I've seen. Rocket Lvl 1 is the best kind of "oppurtunistic kill!" super that this game has (and basically outdoes what Nariko's Lvl 1 should have done in the beginning), and his lvl 2 is great in the fact that it's not easy to dodge at all, with kill potential on the drop, and on the long-lingering Mist that stays around afterwards.
I don't mind the idea that Turrets give the enemey AP when hit. The fact that it distracts the enemey from your players, and keeps them from hitting YOU, is a strategic tradeoff. Yourself or a teammate can kill the distracted player handily, and for all the combo-stopping and threshold-expansion it provides, I think it's worth it. Fighters are generally about balancing risk and reward, and I think this provides a good version of it, for this game.
Fearless does seem like a great stage, and it's funny, as it's Mashup doesn't really stand out to me. Falling off a platform into a lower area feels like... something that could have happaned in Heavenly Sword anyway. The fact it transiations between 2 intimate areas (which seem to be the favorite types for most players) is great, and it's stage hazard (the track) and bounty (the pots to the side) are all worthwhile.
Now for the Fanservice of these characters... Kat's animations are all really cute / well done, I love her fluidly-waving fingers on her first taunt. Her floating victory image is great, and the transition of emotions in her loser portrait is very fitting, and a solid take on what you'd expect of her images in Gravity Rush. I'm not so happy with her victory music, though... it doesn't seem as solidly memorable or tied to the source material as I'd hope. It sounds like "All Stars" version of GR-like themes, but I'd rather just have straight forward GR themes, really.
I haven't seen Emmett's fanservice elements much, but his poses all look incredibly cool, actually. His victory is Boss-like, his loss is setup very well, and the Win Pose that has him sitting on the Hawk is so loud-and-proud that it makes me smile, even when it's from the opponent winning.
Haven't cared much for the DLC minons, I wish there was MORE to them. Like unique from-their-game animations, or a taunt associated with each one. The new models are nice enough, and I might spend some spare PSN points on a few when I have extra, but I can't say I'd rather buy them, than a PSMobile game, or a good Mini, or soemthing... I'd rather pay comparable prices for expanded victory music options, for comparision.
All in all, very impressed with what is on offer here. Superbot's strengths outweigh their weaknesses, to me, and really, I think it's sad to have possibly only 1 more iteration of DLC from them for this game. This game kinda shines in the potential for DLC, and the delivery method on display for this first pack is a great example of how to expand the game without shooting it in the foot with community splintering and ultimately pointless outrage.