The first part of this may have to do with the pathfinding changes mentioned in the stickied thread, but they seem to go together somewhat from what I experienced, so I'm just mentioning it here. I was playing MF mid lane against a Yasuo. When the waves crashed and I was near my ranged minions, they *constantly* felt like they were in the way. MF just would not path into or through those ranged minions at all. Sometimes it meant I wasn't able to dodge things the way I wanted to (couldn't sidestep into the minion waves). Sometimes it meant I had walk all the way around the minions just to get in some poke, or even try to last hit. It certainly did cost me some CS in lane because I'd be just outside my AA range, go to last hit, and then MF started walking around the minions to try to get in range, causing enough delay to miss the last hit.
Now the second part, and I'm not sure if it's related, but playing Cait bot lane, I was having TONS of issues with targeting AAs. These are problems I never have on Live, and I've got all my settings the same for PBE. All I know is that instead of poking Lucian, I felt like I was constantly clicking to have Cait get some pot-shots out on Lucian, but instead found her walking up into melee range of Lucian/Sona, which did not go that well for me. And I felt like I never really could adjust to it throughout the game, either. Odd thing was that I didn't find issues like this playing Corki or MF at all.