I had mild side effects that lasted for about 3 weeks when I first started it when I was 16. Loss of appetite, tiredness, stuff like that. Not the weight gain though! WOO!
I wondered what the withdrawl symptoms were like so I skipped it for two days. Holy. Crap. The brain zaps were crazy, the anxiety was nothing like I have ever felt before, even hot flashes!
I really don't know if it worked or if I improved my anxiety/depression by getting older.