I've experienced it, both as a patient myself and through my mother who was sectioned and hospitalised also.
In my mother's case; well, even though I hate teh whole idea, it did save her life. She was psychotically depressed, had tried suicide, had also attempted to burn our house down (with her, myself and my brother in it). She was taken away in an ambulance in teh middle of the night. I was roughly eight or nine, and petrified. She was held on a secure ward, where we couldn't visit, for six months. She was put on depot medication (had been refusing meds) and came home after six months a different person. I mean different too; I didn't actually recognise her.
Since then she's stayed well. She hasn't taken meds now for maybe twenty years (perhaps longer even) and says herself she's glad they took her in; the treatment got her well enough to come home and stay well. She still has depression; she deals with it in her own way now and it's never been as bad as it was back then. She understands her illness now, and works to live with it and control it. For her, forced treatment gave her back her life when everything else had failed. Hard to argue against it, even though it leaves a very nasty taste in my mouth.
For me it was a nightmare. I was sectioned because I was refusing treatment and was becoming a danger to myself. I believed that I wasn't part of this reality, started cutting myself up to prove I was. Once sectioned, I was given ECT, twice a week, for three months. You do the math; I had 22 treatments in all, came out of the other end no better off symptom-wise but with cracking great big holes in my memory and an impaired short-term memory which still causes problems today, and which I truly believe was caused by ECT. It made no difference to me. When I came home I was still labouring under the idea that I was somehow not real, still cutting myself periodically, and rather confused now to boot. ECT is not something I would ever have agreed to. To have someone fry your brain and be powerless to do anything about it is a terrible thing to go through. I am still very angry that I had so many treatments, when it was obvious it wasn't helping, and with no regard for my feelings at all. I will never let myself go through that again; sounds dramatic but I'd rather die. I am sure they put something in my brain when they did it. They're not going to get the chance again.
So... for me, I have to say forced treatment is wrong. Yes, it did mean I still have my mum; but I think her case is probably an isolated one and here at least forced treatment seems to be nothing much more than a way of making people comply with treatments they don't want. I believe that everyone should have some say in what is done to them, expecially their brains. I know my mum is grateful for the second chance she got; but maybe also had she had the right support to begin with she'd never have needed that chance.
I'm not sure if it's anti-psychiatry; certainly it's anti-psychiatric practices. And this is one practice that really shouldn't happen.