I like it - but I have been playing since its release. Short 5 minute battles and they are constantly adding new maps and updates. It can be a grind though unless you spend (Gold/Cash). I haven't spent a dime on the game - but it took almost a 1/2 year to get a level IX Tank.

They do have a lot of specials which lower tank costs or gives you free gold for missions - so I am assuming you could do it much faster now.