See also Evony Guides
This Update changed some of the mechanics in the game.
1. First, Barbarian Cities (NPC), instead of replenishing their resources in the normal hour, now take 8 hours for the resources to be replenished.
2. Walls: The walls have been updated now to make them very effective and much more stronger. The update raised the Shooting Range of the defenders troops (archer towers, archers, ballista, defensive trebuchet, and catapults) by the level your walls are. If you have level 6,7,8,9 or 10 walls they are now very useful against ballista, as your archers, ballista, and defensive trebuchet can now hit them.
3. Be aware that with this new wall update, attacking level 5 and higher barbarians will need a lot more ballista then before the patch, and you will probably want archery level 10.