I did mirtazapine so I share my experience.
First I was having a "recreational" use so I was taking it occasionally, when I wanted to sleep (15-30mg), it wasn't too strong effect talking, and waking up the next day was easy.
Then I tried to take it everyday for depression hoping to feel a bit better overall, and well honestly, I didn't see much changes (in 6+ months)..The only thing that fucked me up most, was the fat gained, 20kg+, not joking. It was making me hungry all day long. When I realized that, I decided to stop it, since 1) I was still kinda depressed 2) I was a fucking barrel
I stopped it one day and never touched it again, didn't feel withdrawals or other side effects, but it took me a very long time to loose all that fat. And not to mention I was even more afraid of going outside because I was looking very bad, couldn't even fit in my jeans and the belly was huge..very embarassing.
I'm back to classic benzo for sleeping and for now I think I'm ok, never trusted any anti-depressant, I tried mirtazapine only because it was one of the few that wasn't a SSRI, so I gave it a chance.