Coming from a Second Life long term resident, the interface of which I, and many, many others criticise frequently for being unfriendly and illogical, describing an interface as cluttered and hard to use is pretty much the ultimate condemnation. I know the game runs in a browser and that limits the flexibility, but the design of the interface drives me mad. Lots of little buttons to press and the need to change in the middle of doing things, argh! The inventory is badly arranged too - everything takes 1 slot, be it something like plate back and breast (which weighs about 30kg and is completely inflexible) or a meal of shrimps, which probably weighs about 500g. Why not a weight limit if you must limit inventory?
I find the chatting to NPCs to be a real bind for two reasons. Firstly, it takes you out of the normal interface, and gives you limited click here to say this, or here to say that options. It's slow, clunky, and frustrating when you don't want to say any of those things. Secondly, when the NPC gives you vital information it isn't recorded, so you have to record it by hand. What gives?
I find the other players largely rude, often unreasonably aggressive and distasteful. The servers are packed, and everywhere you look it is bustle, hustle and rudeness. I often solo things, even in games where soloing is discouraged, but I can enjoy joining up and having fun when the chances arise. But a game where, in the few hours I played, I found being a female character attracted 3 stalkers, and a load of unwanted advances, as well as being killed by other players without warning or provocation on 4 occasions to be deeply frustrating. I guess playing on servers with loads of random horny 14 year olds will do that. Second Life may have a reputation (and adults with the imagination to carry out that reputation if they choose) but the horny teens are more annoying to me. Linked to the death issue, losing almost all your equipment each time you die is frustrating. Various games have various ways of dealing with this, but it is hard work and something I don't like. Being penalised for dying is right and good, but losing most of your items, seemingly at random is really not the way to handle it thanks.
Is there any logic to the skills trees? Why does burying bones get me prayer xp, whilst, it appears, casting prayers doesn't? What good, apart from more prayers does that do me? Why should I go fishing, lumberjacking, whatever? Well, fishing and cooking gets me food, that lets me heal in combat (something I'm not keen on), so there is some logic there. I guess lumberjacking plus firestarting lets me cook on a long journey, so again, some logic there, but you get the daft situation of players chopping down every tree they can find, filling their inventory then lighting a long line of bonfires just to get the xp and level the skill, and to clear space for more logs in inventory I guess. You can't, of course, force your players to role play well, but do you have to reward them for doing totally stupid things? In other games, even other free to play games I've tried, there is, fairly often, a logic and structure that seems to make sense, to persuade you towards good roleplay and to reward you for it. I would argue that both Dofus and Oberin manage this to a significant extent of the games I've tried recently. It might be hard work, but it's not impossible. Why did RuneScape do it in a fashion that grates so badly? And speaking of handling badly, if you are on a free to play server and you try to interact with people, enter a dungeon etc. that is only available on pay to play servers you get a message saying "This is only available on pay to play servers." I understand this, at some level, because they obviously want to encourage you to pay, but again I have tried other games (Dofus again springs to mind) with the same split structure that handle this so much better.
Of course all of these are very much my personal opinion. As I said at the top, you may find all of these things attractive and if so, good luck to you in your explorations.