It is hard to compare "Loose" to Furtado's last album, since it's like a change of 180 degrees.
While its preceeder was an off-beat alternative to contemporary pop, "Loose" is much more focused on the mainstream music of its time.
What you can say about this album is that Nelly Furtado has not lost any of her power, even though the change of genre.
She brings up granades like "Say it Right" or "All Good Things (Come to an End)", which are both catchy and surprisingly calm - even though the first one has a beat that has Timbaland written all over it, who usually makes a more upbeat sound.
This is all accompanied by a bunch of dancable and memorable club tunes, like "Promiscuous" or "Maneater", even though nowaday's kids should not except a techno-pop sound like Pitbull.
Still, compared to her former masterpiece "Folklore", "Loose" has a few weaker tracks, like "Do It" or "No Hay Igual", that are just fine, but not outstanding. But overall, the amount of great music overshadows the album's so-so tracks.
"Loose" is not foul-mouthed or too graphic in sex, but there is a song called "Promiscuous", which is about what the title suggests, but in a rather flirt-ish manner than really graphic.
Should be no problem for teens.