This is great FPS game. There are lots of fun stuffs such as tank, apc, helicopter, and so on. Mostly, the game allows you to learn the tactical movement as a team. Be a little bit more serious while playing the game, and I believe you'll enjoy it.
Great game. Here are a few tips
1. Frightening skills are usually better than meteor.
2. It is always the hardest at the early stage, so focus on reducing the price of upgrade & gaining experience.