once i ulti'd ezreal in the face when he was starting to channelling his ulti, he gets stunned and a second later i get nailed in the face by his ulti. the skill does have some bugs.

IMO cass's ult should have it's cooldown reduced. For an ability with such a limited fuctionality due to it's limited range on a champ that relies so heavily on staying away from the brunt of the fight to be effective.

But, yeah, the bugs with her ult definately need to be fixed. I've experienced the ones mentioned, and there's also the one that if someone starts casting before your ult finishes they will finish even if they are stuned before they completely, this is best seen against Lux's ult in my experience.