It goes without saying that the reactions to her critique are
grossly inappropriate disgusting, but the substance of that critique is legitimately debatable.
breasts the size of her head (seriously, line that stuff up, each breast is the same size as her face) popping out of her top
It’s true that each breast is about the same size as her face, but heads are quite a bit larger than faces. Inviting the comparison highlights the exaggeration of “size of her head.” They don’t look to me to be “popping out,” either, but about as restrained as they can get in a strapless top. Which, as she points out, is a ridiculous thing to run around fighting crime in.
Those are implants. On a teenaged superheroine. Natural breasts don't have that round shape (sorry, boys).
Thanks for the condescending implication that we don’t know what real breasts look like, but again, these are bound by her outfit. If they stayed that way when she took it off then maybe you could make assumptions about their artificiality, but since she’s an underaged teenager that’s not going to happen.
The rest of it is not off-base. I personally wouldn’t bother analyzing a semi-competent unimpressive comic cover in that detail, but to each her own.