The passive stealth should be interesting, and as long as the range in which she can be detected is shorter then the average range at which ranged champions can attack (500 ish), she should still maintain a lot of what made her unique, and from the sound of it, it hasnt changed too much.
Major Concerns for me that have not been addressed:
1) She has no CC, and instead uses a passive increase to movement speed be dealing spell damage (hatespike) and an on demand movement speed steroid for chasing and getting into melee quickly. This presents some issues.
-How quickly does her passive stealth re-engage. Does it a) re-engage once you are out of the detection buffer zone, b)possess a short reactivation internal CD upon re-entering combat that can be re-engaged by simply moving out of the buffer zone while off CD or c) possess an internal CD that can only be re-engaged upon successfully leaving combat
Depending on how this works, it could be a major nerf. Before you had an 8 second CD (I think correct me Im wrong) that could be re-employed for escape purposes, or re-engaging the enemy on your own terms. If you could create distance, you could escape, even within melee distance by re-entering stealth. If stealth cannot be re-engaged with an internal CD, and while in combat, you may find yourself having to commit to combat without any form of escape. For instance, an 8 second internal cd, 5 seconds to exit combat, and then the time it takes for you to create distance to get out of the stealth detection buffer zone. You see the problem? For ranged champions, or melee with any kind of slows (think tryndmere) it may be extremely difficult, if not impossible to re-engage stealth once you've entered combat.
2) Her new ultimate is a massive trade off. Her old one was brilliant, in terms of thematically for the champion and its functionality. It was a massive attack speed steroid (movement speed as well), that healed you and reset the CD if you finished off an enemy or assisted in a kill. This allowed her to down enemies quickly if built right, and heal up after a kill to take on more. It was fun and interesting.
The new one forgoes the heal and attack speed steroid, in favor of added team utility in a aoe nuke that increases her armor and mr based on how many champions (presumably) she strikes with it. It also has a slow attached. Problem.
a) Using her nuke enters her in combat, disengaging her stealth. She now has to use her movement speed to run into enemy lines and hatespike. The added durability was given for just this reason, making it a poor initiator. It contradicts her stealth functionality, in sneaking in and blowing up the AP/AD carry, and in itself if not used as an initiator, contradicts itself as a ranged nuke.
Your either nuking from range, and losing stealth, or utilizing stealth and nuking from melee. Perhaps it will create an interesting risk/reward dynamic But nonetheless, theres issues to be had.