Wow. Eight pages in twelve hours. There really is something about the Deathnote that is incredibly fascinating to people, isn't there? It poses the key moral question: who are you in the dark, anonymous and beyond consequence? In real life, there isn't likely to be an L to figure almost everything out within a couple weeks.
There's also the terrible irony that the Deathnote provides no protection or worldly power. You can't openly claim it's power without putting yourself at terrible risk. If Light had succeeded at making himself a ruler, he'd've face endless threats and attempted assassinations.
Honestly, I don't know what I'd do. There are people in this world that almost everyone would be happy to be rid of. But at the same time, there's no sharp line between evil and normal. There's no magic body count were you can say "yep, no one else needs killing". The very act of using this thing sets up an inbalance, you either have to accept yourself as a mass murderer (and thus need killing yourself), or claim some sort of divine immunity, piling up excuses like Light did, justifying an ever-lower bar for it's use. I like to think I wouldn't use it.