Depends of where and how you use her she can be top and meh, so there can't be easy one line answer "she is good" or "she is bad" 

I've read online that shes pretty op but looking st her skills I cant see why? Anyone got any experience using her? 

Mainly that second skill - decreases all enemy buffs by 1 turn and increases ally buffs. On an AOE defense-based attack. And then there's her passive with the ally protection and block damage, plus a strong aura. What's not to like?  

That's why you will see her in many CB set ups and not many Arena teams. 

I got her as my first epic opening my first 3 ancient shards and I can confirm that she is a really good campaign and CB character. Her aura is one of the best defense aura skills i have seen so far because its a aura that counts for all battles, her A2 AoE skill that extends your buffs and enemy debuffs for 1 turn is so good and her A1 having provoke and a small heal while she a defensive champion is really good.

Putting her in a life steal set along with a set the either gives her a shield or a set that ignores defense and she is a beast of a champ.

I have not gotten her fully lvled or masteries and combined with Kael i have used just the 2 of them to get me 3 stars in campaign up to brutal Felmin's gate, then again my Kael isn't fully lvled either but they are both lvl 50.

So if you think about it 2 lvl 50 characters, 1 rare and 1 epic have 3 stared all of campaign to about the halfway point of the 3rd tier