To no one's surprise it turns out that changing all the items, masteries, summoners, and runes resulted in some things being too good. Riot has said they want to give people more time to play around with things to see how things shake up but they are going to nerf some of the particularly brutal offenders. The patch notes can be found here.
In particular they're nerfing the new black cleaver item, Teemo, Rengar, Zyra, and Diana. I'm happy to see all of those changes. The idea that just stacking black cleavers was a good plan is just jarring for this game where they tend to make the good things unique to force you to buy 6 different items. Well, it's worse and some of it's power is unique so that objective is probably accomplished!
They're also changing the way you capture altars on the 3v3 map. Now you'll be able to interrupt people by doing damage to them instead of having to go stand on top of them. This is a buff to ranged attackers and a nerf to melee bruisers, albeit small, which I am in favour of. I like that someone like Ezreal will be able to shoot someone on the altar to stop the capture. Before he'd have to go stand beside the melee bruiser and that isn't going to end well for Ezreal!