The quests are more or less the only redeeming thing I can think of about runescape, for a childish game they're challenging and often expect you to do nothing but explore to find the next clue(or cheat

).
The controls are bleugh, for something so simplistic you'd think they'd be less terrible.
The levelling/PvE is grindy and easily broken through using specific pathing bugs or just switching world until you have somewhere to yourself.
The gathering is both mind numbingly boring and semi forced to pay attention.
The community is as you'd expect several years less mature than a community for a game aimed at regular aged immature people.
-on the level of somebody following you around shouting that you smell as a method of haggling
-on one occasion killing another player caused that players big brother or whatever to go onto his account and try to intimidate me for making the original player cry and to give back his things, that or that player was immature enough that threatening people as if he was a 15-16 year old big brother seemed like a good idea.
The PvP is 98% not based on the player.
The maps are overcrowded and pretty linear.
The chat is messy and suffers even more in overcrowded areas.
It's a starting step to online gaming and it does a good job at being accessible but just difficult enough to keep some people entertained. The phrase "they don't know any better" comes up quite a lot talking about it, sure some people will stick with it but most will either realise they're not really into games or find something else on the market that will forever make runescape look kinda pathetic in comparison.
This is from my viewpoint of playing it almost 7-8 years ago(when runescape was only moderately outdated) so if anybody disagrees because something I said has significantly changed in that time, I apologise.