When I was really bad with my depression I was put on 3x75mg per day and struggled a bit to begin with sorting out whether to take it 3 times a day or 2 in the morning and 1 at night etc. Once I got sorted i found it really did help so long as I didn't miss a dose, then I felt awful.
I found it loads better than fluoxetine (otherwise known as prozac) which did nothing other than make me feel worse.
I very very slowly reduced my doses following my GP's advice and had some pretty bad withdrawals for a few weeks but I feel ok now. I honestly believe without it I would still be suffering from my depression, whereas now it's at a level where I feel I can cope with it on a daily basis.