Well, I can't give you an objective opinion, considering it's the name I bear ;) I think it's pretty and unique, without being totally out there.
As for how people react to it- most when they comment on it say it's pretty or interesting. It's not necessarily bad to have a celebrity with your name, if it's otherwise unheard of- it helps people spell and remember it! As long as the celebrity in question isn't negative or overwhelms the association of the name- like
Elvis for example.
My parents actually named me after the Marias river in Montana(pronounced the same as
Mariah) but since our last name starts with an S they took off the "S" and added an "H". Only later did they find it was used by others. This was way before
Mariah Carey came on the scene. So now because of her, there is a crop of Mariahs much younger than me ;)
I'd be interested to see what others have to say about it.