Fiora's new ult. My take on it.
My basic feeling is that a lot of Fiora's survivability was built into her old ultimate which basically gave her free dmg and on hit procs while make her un-targetable.
No that shes does not have this mechanic. Her new ult requires that she stick around to do her work on someone. While this would work out fine in a laning scenario, once the game progressed on to when people are grouping, she would basically have to commit to dying in order to get her ultimate off.
Depending on how her heal works and how strong it is, this will give her a reason to try to proc her ultimate in team fights while also not leaving her with nothing to do besides die should she be successful.
I think there maybe could have been some better options for her new ultimate, but I also don't hate the AOE heal on the one Riot decided to roll out.