They still update the game a lot, after all, Nexon perfected the art of sucking people into the cash shop. Frequent updates are one of the best ways to get people to buy new stuff so it's quite worth it for them to push out new content quickly.
It's been a few months since I last played but the game has come quite far, even for a 100% f2p player you can do pretty well on your own now, especially if you play right after a big patch hits and participate in their in game events. I don't know how long it's been since you played but if you enjoyed it in the past I think it's definitely worth giving another try. I would probably still play, myself, if I had anyone to play with =p
I don't think it is as popular as it used to be, I've had a very on and off relationship with the game, I think in its current state its one of the best MMOs from a casual perspective, easy to learn, levels come easily and just has large amounts of content now.
@pacox, it depends on what you want to play. I love the old classes since I played since Beta (assassin's especially), the new classes are definitely more unique and some have different level caps and I think one can even be reborn or something. But ultimately choose a class you like the playstyle of they are all balanced pretty well and have their own strong points.
Is there a reason to still roll the old classes over the new ones?
From a balance standpoint, not really. The only three classes that are really great in terms of bossing is a Marksman, Fire and Poison mage or Hero. Sniper you need to get to level 195 and then your damage sky rockets to no other. FnP, sort of the same deal. Hero you just smash the combo button.
I still play around once in a while but don't expect anything relatively balanced.
For the most overpowered class, pick Kaiser. For the most expensive class, pick Kaiser. Kaiser has the ability and the potential to make any situation in favor to said Kaiser. He's also not squishy and has an annoying voice. http://www.southperry.net/showthread...d%20%/s%20List
In terms of cheapest gear to most expensive. Bowman > Mage > Pirate > Thief > Warrior.