It looks more mature than Ashley, but I'm not too fond of the idea that it might be pronounced ''ASH-lee-ah'', as that just doesn't sound right. The name COULD be pronounced as ''ASH-lee'', though, with a LONG ''ee'' sound at the end, as normally, it is pronounced with a short ''ee'' sound, and for some reason, names with a short ''ee'' sound at the end come across as more immature than names with a long ''ee'' sound at the end. But that would sound weird because of all the Ashleys with the typical pronunciation. So, it would be better to opt out of using this overused name altogether.
This is what happens when names become extremely overused. Those crazy parents who like the name but decide they want to be "unique" make up some crazy spelling that ends up sounding even worse. My suggestion? Just don't use Ashley or any of its variants at all.