CUTE! They are a little sheer, so I'd recommend skin-toned undies. I am 5'5" and around 110lbs - I wear size XS everything at Target (size 24/00 pants) and...the XS were too small. I mean, they fit, but it was high waisted and NOT flattering. I exchanged for a small and it's MUCH more comfortable and looks like the model. Both tops fit me (the XS and S), but I think the bottoms run small in the waistband. I'd size up for style and comfort.
These pajamas are SO comfortable and cute! I am 5'8" and the medium is a great length on me. They're not too thick or too thin, which is great for the winter or lounging around the house. I'll probably ending up more patterns.