Logged in for the first time yesterday and would like to share some feedback of my overall impressions of the game so far.
1. This game really needs a user-friendly tutorial (which you can opt in or opt out at the start) to teach you fundamental things in the game.
Logging in reminded me exactly of FFXI - it took me a while to work out where to go and what to do (let alone how). I can't imagine how newcomers must feel with such an unfriendly introduction.
E.g. once you hit your first level up, it should step you through how to assign your points, and once you learn a new skill, it should similarly provide a simple walk-through on how to equip them. Also, it wouldn't hurt to put quest markers indicating where to go (guild leves already point you in the right direction and maps are already fully revealed anyway).
2. Targeting mobs is really annoying.
When you're under pressure from adds, it doesn't help that the interface doesn't assist you with targeting them. I found I lost a lot of precious time fiddling around with the tab button and using my mouse cursor to select targets while getting beaten down - if we're expected to commonly defeat multiple mobs at once, this probably needs to be addressed.
3. Mob density feels like it's really low.
This one's probably been mentioned before, and hopefully it gets addressed on release - but currently it's a challenge to find anything decent to randomly exp/skill up on. Or it's a case of me not knowing where to find them!
Other than these considerations, playing the open beta really brought me and my wife back to the magic of the Final Fantasy world (something we haven't felt since FFXI), so for those who are on the fence on whether to play or not, it's shaping up (at least for us) as another awesome gaming title.