It is fun and relaxing for a while as you are very low. But the moment you are worth attacking you will be harassed 24/7. This means that you have to dedicate enormous amounts of online time to have a slim chance of progressing.
There are no fair battles and the higher ranked keeps progress down making the game insufferable after a short period of time.
I would very much like the range in which you can attack active players to decrease and those who attack constantly to have a penalty for preying on much weaker targets.
That being said, the whole build/invest setup is quite thrilling and the progression of technologies makes this a very potentially enjoyable/addicting game.