I think they have a sign that says they are the biggest one in the world, but I can say for sure that they are not. I know plenty of stores that have more stuff.
Don't use such a sign if you are not for sure the biggest one as I was going in with this in mind and after 5 minutes I was already at the end.
They have some nice things, but they didn't had what I was looking for, so I just can tell you what I saw without spending money there.