Overall.. things I like. Slowing down range carries is a big thing in my opinion. If you play a melee with no way to close the distance quickly, you previously weren't going to catch a range carry 1v1. That and almost every range carry has a way to escape even if you did catch them. Add on top of that either an exhaust, flash, or ghost and catching a good range carry is damn near impossible.
Ashe: has stun arrow and slows with every hit. Can kite you indefinitely.
Trist: has jump and burster shot to knock you back. Can alternate one for the other when it's on cooldown.
Twitch: AoE slows and stealth.
MF: AoE slows and ridiculous movement speed.
Kog: Umm.... he has ridiculous range so he can hit from off the screen and run before ever being caught.
Corki: has his teleport/dash ability along with ridiculous range like kog.
Urgot: Ridiculous range to fire off screen with, but he's not that strong of a range carry.
Leblanc: Dashes, slows, snares, and doubles. No catching this one ever.
TF: teleport, snares, and slows. very hard to catch.
When you take any range carry with their plethora of escape or avoidance (such as long range) mechanisms and add on top of that a base speed higher than most melee chars... it's a royal pain in the ass if the melees can't get close or get away. There have been a number of times I've been kited or picked apart by trist, ashe, or MF with no way to do anything. They can be lower level and under geared compared to my melee char and I still can't do anything to them. Sure the melee has either higher armor, MR or HPs or a combination of those defenses, but that doesn't mean squat if you can't fight back. So I agree with the change for this in the patch notes.
I also agree with the major AoE damage team compositions + large lockdowns. Galio/Amumu + Sona + Vlad on a team typically = always winning a team fight. Throw in some carries on that team above, especially with more AoE damage goodness like MF or Twitch, and it's a team that is impossible to beat if the players aren't complete morons.
However, I think the new changes to the AoE game might hasten to newly emerging meta-game. This is the isolation game I've been seeing more and more of. Basically taking champs that can isolate a person of the other team even during a team fight to dog pile on that person. Champs like Blitz, Gragas, Allister, Singed, and Janna which can do this safely I have been seeing more and more of. This type of team refuses to do any team fight that isn't by a tower and is an effective counter to the AoE team to a degree. Still, overall it was not as effective because it takes more positioning to get it right and skill to produce desired results. Unlike the AoE team that can most of the time charge right in, lock everyone or as many as they can get down and then annihilate everyone that was in their AoE sphere. Then they can pick off whatever is left.
But the effectiveness of pulling an enemy champ away from his team mates, CCing + focusing that champ while using abilities to prevent that enemy champ's team from coming to the rescue is nothing to scoff at. Take this scenario. Blitz pulls someone (doesn't matter who but squishier ranged carries are always nice) away from his team. His team does a combination of CC's to prevent escape of that enemy champ. If anyone of his team comes over to try to rescue the enemy then a Janna or Gragas Ult sends them flying back. Now it has gone from 5v5 to 5v4 very fast. One more time and it is 5v3. This type of play style can be done very safely as well. I see a possible rise of this meta-game in the future.