I don't think it sounds bad, and I know that it'd fit in with today's naming trends (well, at least, in the United States), but I'm personally not a fan of it. I don't know why, I'm just not a huge fan of -lee endings (I do think that Shayleigh looks nicer). I do love one name that is very similar to Shealee-
Shayla. I'd name a daughter as
Shayla in a heartbeat, and every met bearer has been very sweet.