I think I'll reserve judgement on this one. I've seen it it far too many times when devout negative opinions are formed about characters and balance based on very limited information. Ignoring the comments of the very few people that have used her, we as a community we have 2 videos of Helena in action, being played by so called "professional" players. I can decide to become a "professional" player tomorrow but that wouldn't mean I could bring out the best in a given character. The play style in this vid looked to utilize a lot of DoA4 habits and very simple strings on juggle. That doesn't mean Helena as a character lacks the tools to utilize DOA5s mechanics. I noticed no CB or sit down stuns. Doesn't mean she doesn't have them. Hell, has anyone even seen Lisa's PB? Still sure she has one. To me it means the players didn't know how to use them. Far too little for me to decide a character is broken or low tier. At the end of the day, I think what will matter is what each individual player can pull out of her.
Prime example: It's a bit unfair of a comparison because VF is built on it's technicality, but Jackie and Pai are considered easy pick up characters on first glance, while Akira looks absolutely horrible in the hands of the inexperienced. We don't bash him because we've seen, and felt, what he can do when used properly. I get the feeling TN may be shooting for a similar effect with Helena. Lets see how it plays out once she been used over a period of time
Maybe I'm alone in this but it seems that people are overreacting based on the opinions of a few and that's affecting their opinion. It's a snowball effect at this point.