The biggest issue I have with the game is that you have to buy ammo. It's not possible to find normal ammo in the levels. I didn't know this at first and ended up running out of ammo in a level.
I noticed that the lag is somewhat fixed if I refresh the page. I've had this happen on several other Kongregate games and it is usually caused by one thing: memory leaks.
I like this game, but I really think the world maps should be in order by difficulty of the levels in them. One map had the first level at a difficulty rating of 14, and the map listed after it has a difficulty rating of 10 on its first level.
I really enjoyed the first game, but the forced multiplayer this time around killed it for me. I kept disconnecting from races and got NOTHING from them.
With the way the game works, I found putting your strongest attacker in the back row and attacking only with them is an effective strategy. Your hired party members will take a majority of the damage dealt, and your strongest attacker will stay alive longer.