A key difference I find between STN and LTN is that the people I know that moan about LTN use it, those that moan about STN dont and just assume it's bad. That said, if they try flying out of STN early morning and returning after 11pm they'd be right. Any other time of day they'd be fine.
A complaint of people I know that do use STN is the trek through duty free, even though they have to do the same at LGW which they insist is better.