Welcome to the WoW main forums- congratulations on making the switch.
Please forgive my fellow posters- we tend to see this a lot, and it
is in the FAQ for that reason. However, you have a grand total of three posts, so you may not be a forum regular, and may not have known to look there. It's always a good idea to check the FAQ and stickied posts before asking questions on forums.
You can check my usual response to FFXI converts
here.
For testimonials from former FFXI players who converted, click
here.
This page is a little dated, but should give you an idea about endgame content.