This yarn looks lovely with yummy colors and the skirt is very cute. Personally, I have a love/hate relationship with cotton. My area is hot most of the year & cotton is the perfect fiber. It's the lack of "spring", that you find in wool, that is hard for me to accept. If your pattern is specifically for this yarn, it's should work.... but I'd still expect some sagging. Sometimes I mix a finer (lace weight) nylon or rayon to help.
Yes, I'm with you on that! Fell for the pretty colours but really in my heart I know a cotton acrylic mix would be better.....
The pattern does say it's suitable for cotton yarn - decisions, decisions and so hard to choose colours online.