My biggest problem with the Sej update
It looks like she's going to be forced to camp top during the laning phase because that's the only place you can reliably find another melee champ. Mid melee assassins attack a little, but most of their power is in their skill combos so I don't think they are care so much about duking it out in melee. There's no guarantee you'll have a melee support either. Her new power is kinda wasted in most circumstances.
I think all this adds up to her being a very difficult champ to main; I think she's just too niche now.
She needs teams to pick around her. _ I can tell you now that this isn't going to happen in solo queue._ Second she's going to be forced to gank top mainly as that's the only place you can expect to find another melee on your team, meaning you are making bot that much more gankable and you are sacrificing dragons in a lot of cases... or just going into situations underpowered because your 3v3 doesn't have the type of teammates you need around you.
The most frustrating thing about her new kit is your all melee aram team will never have a Sejuani on it.