Most of this will be focused on cities as that seemed to change the game the most. There are a lot of debt cards in the cities expansion. These are effects that can for players to pay cash or accept debt which are negative victory point markers. People were going nuts for those, often playing them just so they were not the victim. I think that was a bit goofy on their part, a negative victory point or two may be bad but it is still less than the positive you will get by playing and even middle range victory card. Don't get me wrong it certainly added fun to the game which is normally very low interaction. I just think the players over valued those cards.
On aspects of cities that I didn't car for was the diplomacy token and cards targeting military victories. Those seemed to address the wrong problem, sure you can get 18 points out of military victories, but that is nothing compared to scientific guilds. Those are the problem! I almost wish they came up with an age 4 expansion that focused on disasters to combat scientific victory. There is a critical mass there that is hard to challenge once it occurs.
The wonder pack is nice as it adds more variety. Don't think any of us felt over powered with the new wonders. I had Manneken Pis, my friends had Stonehenge and The great wall. I will say the Great wall has a pretty crazy ability with the side that allows for getting the diplomacy token. Since you can build any stage you like in any order with the wall it is easy to hold that diplomacy until when you need it.