I wouldn't say that there are any 'bad' areas of Marple. One of the reasons why we moved here over 10 years ago.
Its a great wee place - a bit of a secret really, tucked away as it is up the 'cul-de-sac' of Stockport Road. Its not trendy, but it is a real community and offers something for everyone.
My only advice is, if you are thinking of moving here to commute any distance by car, get ready for some early morning wake up calls! Traffic in the peak hours during term time towards Stockport and Manchester is frankly beyond belief.