Yes, I did. I didnβt have too much trouble with starting Quartet, but I had also been doing a lot of reading of native materials, as well as learning grammar from reading Satori Reader.
I would say, generally, Quartet 1 is a step up in difficulty from Genki. The chapters are twice as long, and the readings are more difficult. If you check out the old Quartet study group, it looks like several people found the book to be a challenge at first. But as long as you keep going at your own pace, and reading native material on the side, youβll be fine!