One of my RL friends played Mabinogi for a while, and said that much in Atlantica, be prepared to spend hundreds upon hundreds of dollars if you want to get anywhere in the game, ever.
The graphical stuff may purely be a look cool thing, but they have a rebirth system, and you have to use to actually get stats that matter. Using something like a $20 item, you can get stats every few days, or you can do it naturally... every few MONTHS. Additionally, you have to keep paying for stuff like inventory expansion, and yes, it will lock your items out, including blocking you from finishing quests if you don't pay to reopen the slots.
I haven't personally tried it, so he may have just not given it a full chance... but to say the least, that doesn't sound good.