WELL...
I am actually in the process of removing my stories from Wattpad.
It's great for posting Original Stories, but as far as fanfictions go...it's a hit or miss, because there aren't specific categories to place your fanfics in, which makes it hard for readers to look for certain fandoms.
And although there is a decent mix of age ranges, I feel that most of the users (at least the ones frequenting the forums) are young teenagers or maybe even younger than that. :o
It's great for aspiring authors with their own work, but it's "meh" for fanfictions.
Still you should check it out for yourself~
Maybe you'll have a better experience.
Just a fair warning: It's hard to promote your own story on that site because you have hundreds of other people trying to promote their own at the same time.
I hope this helps~