I've been playing it since the Open Beta.
At retail release it felt very unfinished, it was rather barren, lacking in quest content, very unresponsive and laggy UI, general difficulty balance issues as well as lack of reason to party and very inconsistent rewards based on effort in battle. Incredibly disorganized player-based market making it nearly impossible to find items. This is just in general, I could go on all day about specific problems.
Square-Enix is actually showing a significant amount of effort to actually improve the game though and actually listening to the major complaints. The game already feels much different than release, in a good way. In the most recent update they fixed the UI, making it now much quicker and more responsive, menu lag as been greatly decreased. Many battle abilities have been improved to be effective. Experience/Skill Points have been made much more consistent.
I'm enjoying it a lot overall, but a lot of that is due to playing with people I've known for years since XI. It has quite a few good thing stuck in there, such as the battle system being fairly active and engaging. It really just needed more time before being released.
I wouldn't exactly recommend the game at this moment in time, it is not as bad as it was to begin with, but it still has a ways to go. If they keep up their effort though I can imagine that it will be in a much more respectable form by the time the PS3 release rolls around. I can't say that for certain though, so make sure you keep a close eye on it around release time.
