I got one last week!
I am not due till easter but thought it is such an awesome idea especially since my daughter is a dancer & I often take her to competitions on my own. If I have the baby on my chest & my arms free then I don't have to worry about moving the pram from the hall to the changerooms & back constantly. Sometimes she only has 10 minutes or less between dances so can't be stressing about bubs as well.
I was playing with it with one of DD's dolls & took a couple of tries but it works well. Seems fairly stretchy & that was my only concern so being the nut I am, I just went & put it on again then put 3 2L bottles in there & it held really well, it only stretched to hold them, no sagging.
Even though I haven't used it with a baby yet I am definitely happy at this point.
HTH