The material doesn't seem "flimsy" to me, it seems more airy. It's really light and the perfect PJs to wear during the summer. The pajamas just look beautiful on all the dolls. The slippers are a bit of a pain, but they don't seem to slip off much on my Mia. The only problem I have with them is that it's hard to stand her up in them because there's no defined foot area of the slipper.
I love a lot of the little things on the outfit, too. I thought I wouldn't like the flower decals, but they're so cute! And the top is a really nice piece (it would work well as a layering piece for every day wear). The lace at the top of the bodice and the small cut at the bottom are both charming. The only thing I dislike about the top is that it's a little too low-cut for a ten-year-old. And I do kind of wish the ribbon had been made of a different material than the rest of the shirt. That's the one place I dislike the delicate fabric.
Edit: BTW, I don't think they look too much like Jess's PJs. The pants are a more gaucho style, very loose and airy. As for the tank top...well, let's just say the Jess appears to have much more modesty than Mia.