as far as live servers are concerned, they are populated and been around for a long time. if you wanna start playing this game your only option for the live servers atm is Naya cause chronos is running at full capacity and they temporarely closed character creation on it.
now if you wanna know if its really worth playing?...if you are looking forward to pve content, it is yeah its interesting and nice till a certain point your gonna have to get betteer gear then the freebie to keep going....but if PVP is your thing then brace your self if you wanna be competitive...some of the players have been here for a long time and been gearing up threw time.
in the end it all depends what your looking for and how far you wanna go in gearing up your character....but dont get me wrong, it is a great game still, even after 17 years, with its good and its flaws.
this is just my 2 cents, i hope it can help you in making your choice