I can't give a lot of details because the NDA is still in effect.
But I will say, it's nothing like the launch version, not even close.
It feels like an entirely new XIV, and quite a good one at that. Esp the engine and interface, 10x better then vanilla XIV. And is much easier on PC hardware then vanilla was.
Beta sign ups are still in progress, go sign up at the FFXIV lodestone and see if you get in^^ sign ups are for both the PC and PS3 version. And there's a new benchmark program to test your system, my system scored almost twice as high as the vanilla FFXIV.
There is a lot of testers supporting the games progress thus far. It has it's ups and downs like any game, and it all comes to personal taste, but a lot of people I know in the beta are committed to a subscription this summer, and I'm swinging towards the same.