I like it. (I assume you're referring to it on a girl because of the comparison to
Hayley. I've seen it on both but prefer it on females, provided they fit the "type" I associate with it.)
I don't think it's too much like
Hayley. They give me totally different vibes.
Hayley is girly, pink, and a bit 'wimpy' if that makes any sense.
Harley gives me more "badass" (probably because of the biker association), and primarily reminds me of
Harley Quinn.
There are only some "types" that I'd like seeing the name
Harley on, however. I would definitely not like this name on a typically 'girly' person. That's one reason I'd hesitate to use it even if I liked it enough, because unless I could predict that my daughter was going to be a tomboy or a biker or something I wouldn't want to give her that name. (same goes for frilly names--they just don't fit all types.)
Harley JadeHarley BriarHarley AndriaHarley Onyx
Harley RoseHarley ElaineHarley JaneHarley Marquette
Harley AlexandriaHarley EbonyHarley KarinaHarley AnnetteHarley LisetteHarley JoannaHarley EricaHarley DahliaHarley NicoleHarley JoanHarley AlexHarley MarieHarley AmberHarley BrynnHarley MeiHarley AderynHarley Dresden
Harley LisbethHarley ElizaHarley Serene
Harley SerenaHarley Luca
Harley is a strange name to find mns for... I don't know if I actually like any of those. *shrug*