They are a very different but interesting way of approaching oil painting.
One way to kind of begin to get the feel for them is to use a product by Winsor & Newton called Liquin. There are now 3 or 4 different types, but I haven't explored all of them. The original Liquin is what I used when I traveled for Winsor & Newton many years ago and demonstrated alkyds for trade shows, Tole Painting conventions, etc.
Anyway, it mixes with regular oils as well as alkyds to make a faster drying paint. It makes your oils act sort of like a cross between oils and acrylics. You have to be ready to make some adjustments!