I didn't find Melfi to be that likable, honestly. Just because someone's not a criminal doesn't mean they're sympathetic or likable. Actually I found Tony much more likable than she was! Her dumping (as a patient, of course) of Tony in "The Blue Comet" was unprofessional and downright cowardly. She didn't have the guts to tell him what was really bothering her (the study she had read about), so she provided completely bogus reasons for dropping him as a patient. It was a really shitty thing to do.

Additionally, I didn't admire that she didn't tell Tony about being raped. And to those who say she did the "moral" thing, remember that this man could easily haved raped (or killed) another woman in the future. If your daughter was raped and/or murdered, and you learned that Melfi could have prevented it by telling Tony what happened to her and who did it, you would hardly think she did the right thing by keeping quiet.