There is a large selection of sizes from which to choose - I used size U to start.
I sewed a "muslin" from some scrap knit and followed the pattern exactly for my size. They fit! Amazing! I tried the older Jalie panty pattern and was not impressed, so this was a step in the right direction. After the first pair, I took a pair of current store-bought panties and compared them and drafted a new pattern. There were slight changes. I did like knowing a recommended length to cut elastic for the legs and body.
The instructions were easy to follow. I tried serging the side seams but didn't like the lump. Then I tried flat locking the seams. That worked well. What actually works best is when I just overlay one piece of fabric over the other and zig zag on my regular machine. Seams lays flat and it's much easier to sew that little piece of side seam than sending through the serger. I also tried putting on the elastic with my overstitch machine and with the serger - that would take more practice to get right. I finally just zig zag them on the regular machine. Easy peasy!
Now whenever I make a knit top, I get undies from the scraps. I love being economical!
I have sewn this about 8 times with 4 good pair of panties from it. I have 3 more cut out and ready to sew.