S4 right now is at its lowest its ever been in terms of population and gameplay mechanics. I'd say stability to but this game been plagued with a long history of abuse so i am not sure lol.
It will quite LITERALLY take a mircale to resurrect this game to ANY kind of saving grace.
Other than the guy who is crashing the servers I really don't see what is the issue with it. it can use some balancing and more content but nothing is really wrong with the game.