They've been around for long time and have only been getting better over the years. The trend is towards safer material. I remember taking oil classes in school where you'd have 40 people each with a coffee tin full of turps in an enclosed, windowless room.
The only difference is the medium, generally it's a type of vegetable oil instead of linseed. They aren't really as water soluble as an acrylic would be, but you don't need turps to thin and can clean it with any dish soap that'll cut grease.
If you use brand A oils or brand A water soluble oils, the pigment size and quality will be identical. Go to any art store and grab a tube to test out, almost every brand makes them now.
I've had some last months on a wet pallet and the if you buy the better examples, you won't be able to tell the difference.