L2 is absolutely worth it. The best part is that you get to support this wonderful game.

Other than that, having the ability to schedule (almost) unlimited amounts of actions is great. It allows you to set up far more complex attack strategies, and it also allows you to stream production from factories to where you need the drillers.

It also allows you to play as many games as you want at once. Some, or perhaps many, might say that this is not necessarily a good thing (you can absolutely overload yourself); but I generally like to play in two games at once, one nearing the end and another just recently started.