*Waits impatiently for new Sejuani to stomp with*
More tankiness, more C.C, more damage that comes out faster [And her Winds HP scaling is better as well as coming out faster, even if it doesn't increase on frosted targets], and her Ult stunning everyone for the full duration [If it hits, but considering I almost always hit Ashe arrows and Varus Ults...]
When new Sej comes out, I am going to faceroll with it. She's pretty strong already. I already dominated most of the time on her. My K:D:A on Sejuani is the highest I have... something like 6:1.
On the other hand I dislike what they are doing with Trundle. They basically, as it says on the page, made an Ice Trundle skin, then decided 'Why not ruin who Trundle is and throw him in to celebrate Lissandra coming out!'. Trundle was a unique character with his own charm.
It's like they changed Karthus, and removed the mystery of Evelynn's origin, just to throw them in with Elise's release.
A character should not have who they are rewritten just to accommodate a release of a character that wasn't even linked to them in the first place. At least, unlike Karthus, it seems new Trundle is actually linked with Lissandra [Oh come on we all know she's the Ice Witch, or at least is behind it]
EDIT: Her Northern Winds is 16% bonus HP, not max HP now. Meh, still strong and looking foward to smashing some people with Sej.