It's alright, the graphics are very nice for a free MMO, it has a unique pet system and job system, but again it gets repetitive by the time you're 20. I couldn't play past level 28.
I heard it eats up too much system memory, like - for a game that's not that good visually or gameplay wise - you need a **** ton of ram to run it smoothly.
I recommend FFXI lawlz
but seriously, my favorite free MMO would be the UO Private Server called Mythos.