I think it's proper for me to go first, no?
The main benefit is the sense of ease.
This allows unwholesome kamma to be let go of as well, I think. Therefore it allows one to go deeper into one's mind, or into the different areas of one's mind, as binding influences are loosened up. Or, what I meant to say was rather that it allows your mind to deepen, all sorts of things can come up, not just the ones you prefer. Maybe a suitable analogy is this (at least it's a fun one): Say there is a parent that is prone to keeping tight watch over his kids, and he does not let them wander, and he also doesn't let them try things for themselves even when under watch--it must be pre-approved for the child to do it ("Did I say you could play on the swings? Ask me first next time."). If he is happier himself, or more at ease, he will be more prone to let the kids do for themselves, at least, not have such a grip on them, which is not to say sit at home reading the newspaper while his kids are doing he doesn't know what, but the tension is relaxed.
I would be interested to hear the effects of this over many years, not just a few as I have practiced.
I think for many it is lying that is the hardest. Serious lies aside, I used to lie in a kind of game-like manner, however it was so much it was insidious. The process to reverse this led to an overly bullish refusal of lies, checking syntax etc. to see if what I said was false.
Perhaps alcohol is tricky for some... I believe it's quite popular, at least in college it was and at parties, and popular "casual" glasses of wine etc.
Sexual misconduct: Err, okay this is one where there has been debate about if it includes masturbation for laeity. What with our internets and city anonymity there is more than enough opportunity for this. Also some people have fetishes.
Killing: Don't kill!
Stealing: Don't steal! [I have thought of this and a separate question related to stealing, which my mom asked me, occurred to me, so I'm going to pose it in a separate thread.]
Feel free to talk about this in terms of intention vs. action, but preferably in terms of importance, cause-effect, relevance, not "what counts as a transgression."