It depends on a variety of factors, but in the main... If you cold-turkey them (which I have done before) it's extraordinarily unpleasant -
Brain zaps being one of the stranger consequences. Physically, you just feel, well, really ****. This whole process should be over in about a month or so.
If you do it carefully (tapering the dose down), then the effects of stopping can be essentially negated, aside from the obvious problem (in both cases) that the depression is likely to come smashing back, which is what happened to me several times when I stopped previously.
But still, I don't wish to require what are tremendously powerful psychiatric medications for the rest of my days. I'll find a way to get these pills behind me...