Iron - do it, it's only $20 on steam, slightly more than a month of WoW. I have recently come back to FFXI after being away for 9 (!) years. In many ways, not much has changed, the game is still very fun as I remember it (when the internet was "young").
That said, I must forewarn you since you are coming from WoW:
-The UI and controls are going to be a huge adjustment for you. Forget your mouse, it will only betray you. There are not UI addons to make the game easier or increase your quality of life. Plug in a gamepad or learn to use the numpad/arrows + wasd. Working through the menus is a bit like moving from an automatic to a stick shift car - in that it is very tactile at first (Do you want to do this? Yes/No. You are now doing this, Okay? Yes/No.) but you WILL GET USED TO IT and it isn't such a big deal.
-The game is casual friendly, this didn't used to be the case. Death/failure will be more punishing than WoW, but come on, that game is bowling with the bumpers up. Soloing is very possible but I urge you to find groups/alliances(raids) as early as possible.
-Use the books located near the zone-in, those are your "leveling quests." In WoW you had kill 10 wolves, get 500 exp, same idea here except it is truly monotonous with zero storyline. That said, it speeds up leveling immensely. When my friend told me he reached 99 in two days played, I said he was full of sh*t. It's true though, it is possible to turbo through leveling if you want to do endgame, and you will no longer spend days getting one or two levels (though I am admittedly nostalgic of CoP ffxi in qufim, dunes, etc.).
-The crafting is deeper, more time-consuming, and more rewarding. You don't have to do it, but this generally becomes your money maker as leveling jobs (classes) becomes expensive. Fishing is a good place to start/cooking, it benefits everyone.
-Be a Hume for your first character. Why? Imagine if your main in WoW could be any class. This is FFXI, and odds are you will want to try most of them. Hume are versatile and will allow you to play any of the classes without any real detriment. Other races must take attributes/HP/MP into consideration. Both times I have not rolled Hume, and regretted it!
-Most of all, be patient, and ask for help! The most noticeable thing about the FFXI community is that there is one! WoW has deteriorated into a me-first machievellian loot pinata type game, and the community has turned to sh*t. FFXI players rely on one another to get things done, thusly have learned to work together. You will run into japanese players, in which case you can complete words/phrases by typing G-a-l <Tab key> and it will translate Galka to japanese. The built in translator is great.
-lvl 13 sorc
-lvl 9 war