I have played a few games with her already and I feel that she is incredibly fun to play and her kit just makes her combos simply heart-wrenching.
My initial thoughts:
1. Her q has massive range. When fully charged, it is better than flash.
2. Her w is percent based (high percent based) and procs everything (turrets, inhib, nexus included)
3. Her e is simply OP. It clears waves in no time (it is 1.16% of AD). Not to mention that it also procs everything (turrets, inhib, nexus included.
4. Her ult isn't insane, but the ratios are pretty strong. It can be nerfed, but does not have to
5. Her passive is also amazing. It's basically a malphite shield (stats are same). Though it is time tiered. it is 18 seconds at start, but by end game, it is like 5 seconds.
6. She also has an attack speed boost built into her w. Every third hit, she drops armor, attack speed, and damage. In return, she gains all three. This probably needs to either be nerfed in stats or amount (she should only get 1 or 2 of these instead of all three.
7. Black cleaver is straight OP on her. but that is the norm for bruisers right now
8. I think it's a bug, but you can get Frozen Mallet to proc off of her q as well as the aoe damage on her e
9. In conjunction with everything else, she has 350 movement (base) so she can run you down lvl 1
10. Other notes. The only other thing that I found that may be worth noting is that her base health regen is pretty strong, but it's not terrible. I could go either way with this.
Simply put, she is incredibly fun to play. But for right now, she needs a bit of work (I think). The only thing keeping her from being the most OP champ ever is the fact that she doesn't have a significant form of lifesteal. With a little tweaking, she can become a pretty solid addition to the League.