Having thoroughly enjoyed Bethesda's Fallout 3 and Oblivion, I've had my eyes on Borderlands for quite some time as another fun game in the first person action-RPG genre and in that regard I was pleasantly surprised.
Unfortunately, after having played through it I can not in good conscience recommend it to anyone, nor will I ever play it again. While a great deal of violence is to be expected in this genre, the violence is virtual and can be largely ignored. However, not even the game's M-rating could prepare me for how... crude... parts of this game were. Pretty much every character in this game swears like a sailor on a regular basis, and the "humor" is so obscene and frequent that it's impossible to ignore. Without getting into too much detail, not only do the characters in this game make jokes about rape, but I was particularly offended when I was sent on a quest to fetch certain "magazines" that the NPC's wife had thrown out, and again, that is just the tip of the obscenity iceberg.
I certainly wish the developer had included an option to tone-down the M-rated content, because otherwise it was an enjoyable game. Unfortunately, said content was so... pervasive... that I'm not sure that would even be possible. Certainly I worry that the stylized cartoon-like graphics would lead an inattentive parent to pick this game up for their child.
In short: if you value you or your child's moral sanity, stay away from this game.