I bought a jelly-roll once and made a quilt for my great granddaughter before she was born. I still had to buy extra fabric for borders, backing, etc. There were strips of fabric that I wouldn't have chosen but it all coordinated so it turned out just fine. But, I don't think I'd buy another one.
I'm sure there are patterns for quilts specifically using those cuts but I like to design my own.... it just seems to take me longer to figure a way to get all the pieces to work in a quilt I want.... and there's always the cost involved. I'm retired so I do try to save a $$ as much as I can.
But, if you don't like to cut your own fabric, or money is no object and you like using patterns and not designing your own.... it might be a good choice. Try it.... then decide whether you'll buy them a second time. We all have our own likes and dislikes.