Yes the new characters are pretty strong in their own ways. Centurion gets lots of confirmed damage off a charged heavy or a wall splat. So does everyone else in some way. Shinobi is really freakin' fast and gets bits of guaranteed damage off of kicks that are mostly unpunishable on their own.

There are plenty of ways to play against these characters, and all you people out there saying this or that is broken is what would dumb down this game.

Against Centurion, expect the kick just like you would predict a warlord headbutt, it's practically the same but slightly different timing (easier to react to imo). Dodge sideways and see if they go for a heavy attack off the kick miss (you can do that) and either parry it or go for a gb if they don't, since it'll be free. Other than that, don't get close to walls because that's where he gets the most damage.

Against Shinobi, play extremely carefully, especially in terms of your positioning. Learn to dodge the kicks on reaction, as that's how you're going to kill them. Currently, Shinobi players generally expect you to dodge and go for a gb and so they'll throw out the free heavy and it'll hit you. Instead, wait for them to make a mistake and punish them, hard. Shinobi is meant to be that extremely complex class to play but really strong if it doesn't make a mistake. One mistake against certain characters is instant death as Shinobi. Always be ready for the kicks, especially the second one since it'll give them a free gb and the heavy + bleed combo (which is a ton of damage). Make sure never to dodge backwards against a Shinobi, as their kick will track you no matter how far you dodge. Stay in your zone, make sure there's a little bit of space in between you and the shinobi so they can't spam lights like a PK, unless you're really good at parrying and can do that stuff consistently. Bait out their kicks with feints and punish them for messing up. It's actually way easier than you think.

Seriously, give it some time for everyone to really learn how to react and punish the new characters and you'll all see that they aren't broken, at least not in 1v1. I agree something needs to be done for them to not be as strong in 4v4, but it doesn't need to be anything drastic. Just a way to not get permanently stun locked by 2 centurions.