Some pros: quiet, beautiful scenery, free
Some cons: bumpy roads with the possibility of getting stuck, far away from supplies, requires a bit of research to find good spots
Given a choice we would always chose boondocking over a campground but it's not always practical.
One of the best places to try it out in in Quartzsite.
http://www.ci.quartzsite.az.us/That experience is not the same as boondocking in a less populated and remote area but it'll still give you a good idea of whether you'll like it or not.
We have never had anything stolen or any problems with strangers or wild animals. Do NOT shoot first and ask questions later. If you are that afraid you should not be boondocking.
In many places it's illegal to dump your gray water tank on the ground. Gray water stinks and may attract animals. If you wash dishes in a pan it may be okay to disperse that water away from your camp. We can stay put for five days before we need to fill our fresh water and dump our holding tanks. The legal limit in most places is 14 days.
I like this site for determining who owns the land -
http://publiclands.org/ National forest service information centers are a good place to find where you can boondock too.