Lets be clear: I love RO. My username is a result of my love of RO. I played on iRO all those years ago, and broke into tears when I hear the Prontera Theme for the first time in years.
Thing is, all that love is nothing more than rose tinted glasses now. This game is old. REALLY old.
Old time Thief players (like me!) will easily understand that much of the combat is literally just "Right Click, AFK" Sure it gets more involved once you go up against MVPs and play in PvP/WoE, but fact of the matter is that you still have to chew through the leveling to get there. Fast travel is still "Blow entire newbie fortune on Kafra, or blow entire newbie fortune on FWing spam". Unless you're a Priest. There are also really archaic mechanics like how spell channeling is completely cancelled when you take damage; dumb fact, but that's the whole reason why I hate Mages to this day.
Thankfully, at least the graphics aged well. The styalized look somehow managed to hold up for more than a decade, and the game itself could literally run on a toaster. Also, you don't have to deal with ye olde iRO "Server Connection Failed" shenanigans as often as we used to, nor do you need to deal with a steep grind (by today's standards) due to the questing system...although said system is rather haphazardly cobbled together.
If you're an oldie, at least Warp Portal set up a Classic server because you'll be completely lost on the Renewal ones. Quests are nice, but mob spawn locations and even spawn power were COMPLETELY overhauled. Simple example: Zombies are now less dangerous than Skeletons. The level of a Kobold is roughly 3x higher than it used to be. At least Porings are still Porings...