1. Limited inventory: 150/200 item limit makes it not worth "living" the game. Having no possession except your gear makes an arcade shoot-them style game. This is a fundamental flaw which has been copied from WoW verbatim.
2. Voice acting: I'm lvl 40 now and I'm getting bored with the game already. All those nonsense dialogs do not make the game more endearing. This is a model that cannot be maintained even if I enjoyed the dialog, which I don't. What I hate most is the made-up languages---if I'm going to sit through a dialog that I really don't care about, it'll help if I was not ""forced" to read it too.
3. Bugs: As it is, it is hard to win a fair fight. That is a good thing; except when u loose a fight because of a bug! My experience so far is mostly with PvE where a NPC gets unlimited health regeneration (impossible to kill) or when my attacks incur a cost, but do no damage (not interrupted, they simply do no damage but go on cool down).
I assume #3 will be fixed over time. I assume #2 will not be a major problem when I get to 50. However, #1 is a fundamental problem with the game. Unless they introduce plants in which you can have a house with inventory in the range of 5 to 10 thousand items, I don't see myself playing this game for long. But that means creating thousands of items worth keeping!
And by the way, fix the chat window...it is non-functional by design.