I haven't been playing very long, but the one single thing I'm finding really awkward is the chat.
I agree with the rest with regards the /tell pop-ups, they're a nightmare, I'd like to see tells incorporated into the normal chat window but displayed in a different colour to enable them to be distinguished.
I'd also like the ability to click on a name in the chat window to instigate a tell to that person (eg clicking the player's name pastes "/tell <name>" into the entry field. I know that's copying WoW, and I certainly don't want this game going down the WoW route, but I have to admit that chat was especially intuitive and easy to use in that game.
I got invited into a guild last night, and I had a nightmare trying to cope with the pop-up chat windows, while I was grappling with the windows and trying to respond to people the group had run off without me realising and I couldn't see which way they'd gone. Some arrows on the radar to show which direction the other group members were would have come in handy.
I'd also like to be able to display a 2nd separate hands bar so I could display more buttons at the same time.
Would make life a bit easier if the button size was enlarged in the hands bar too, they're very small.
Finally, there seems to be a sudden jump in mob level around the Matis starter area, there's a large area of very low level mobs that give me 50xp or less, then all of a sudden I bump into a load of gingos that flatten me in seconds making levelling at 46 fight somewhat awkward (I'm getting more dp than xp at present - I get jumped by 1, then while I'm killing that one 3 others appear from nowhere), I'm all for a bit of risk, but that seems just a bit excessive !
All in all though, great game
Ooh one other thing - I joined a group trek accross the world, and it wasn't til we reached our destination, I logged out, and logged back in later, that I realised I was completely stranded with no easy way back - maybe you could add something on noob island that teaches people how to buy tp tickets ? I didn't realise I should have bought one before I left, and I didn't know how to either. It took me forever to get back "home" and gained me 85,000 dp in the process.