I was on finasteride for 3 and a half months. The sides were, love handles, puffy chest and tiredness. Nothing I couldn't handle though, and nothing that a bit of Arimidex and gym work couldn't sort out.
When my finasteride supplies were running low, I decided to shift things up a gear and get onto dutasteride at the maximum dose (5 pills a day, 2.5mg). My side effects are now LOWER than they were on the 1.25mg finasteride I was taking.
I know that sounds daft, but that's my experience. I think finasteride was doing something else to me apart from lowering DHT, it's the only explanation apart from my dutasteride being fake (I got it from UP and they have a v good reputation though).
2.5mg of dutasteride a day regrew a sh1tload of hair in the trials. And that's what I need, really. The way it's going, I will be completely bald in two years if I don't take pretty drastic action.