You can easily hit someone with 3 autos by slowing someone down with your E before level 6 and after level 6 it only gets easier since you have two dashes. Not to mention that E is getting its CD reduced at all ranks, reaching a 7 second cooldown max rank if you get 40% CD reduction.
There isn't a nerf on her attack speed, as her innate attack speed is being buffed. They're just transferring the attack speed back to her innate stats, which as the other commentator mentioned was how Diana originally was (and it was better, since a varying attack speed made it trickier to AA, since you could accidentally AA cancel yourself).
The only big nerf is on her passive's damage. She won't scale as much due to that reduction in her AP ratio. However, she's getting more movement speed in return, which means greater chasing capability or even maybe an opportunity to run away after doing 3 autos - which is really good because she doesn't have a way to back off from a fight after engaging.
Also, she's getting more mana throughout the entire phase of the game, meaning that she should be able to stay in lane longer. Her mana regen passive sucked anyway, because it only became relevant in late game when you had like 500+ AP which was ridiculous. Her issue with mana doesn't come in late game since you can just build mana, rather it occurs at early stages, literally forcing people to go for multiple doran's rings and so on. Flat mana early in the game actually adds a lot of overall damage. So, it's a buff in some way.
Overall, she's getting less burst damage scaling but she's getting more movement speed and more consistent attack speed along with lower cooldown on her E to slow people and stick to them. If you add the slow + her movement speed, it means that she's become more of a bruiser and less of a 1-trade burst mage.
This should make it even more important now for people to get Nashor's Tooth on her, but we'll just have to wait and see.
RIP
