The tension in this piece is excellent. That is my favorite part about this, the story that you tell within the confines of the page. Your skill and technique is flawless; I scanned the page looking for any errors in anatomy or light sources but everything is really solid!
I do think that the 'spidey sense' waves are unnecessary though, you get the point of Peter's anxiety across well enough by his facial expression and relation to MJ. Unless there is a threat that we (the viewer) is unaware of, why are they there?
If this piece is part of a book (not sure, but I think it is?) is it going to be colored? If so and more work is going to be done on it, please ignore my following comments. Mary Jane is a redhead, the archtype of whatever a redhead is supposed to be, and her hair seems a bit 'blonde' in this piece. If this artwork is strictly grayscale, I feel that her hair should be darker in tone. On a separate note, there is a lot of white space in this picture. It is really distracting for me because the whiteness competes with the other visual elements in the piece. There couldn't be like a painting or window or even a wallpaper pattern to help frame and separate the elements? Again, if this piece were to be colored I think that both the white space and hair color would be fixed by default.
I mentioned the facial expressions, and I mean it when I say that the detail and your ability to capture the tension is paramount. Really good work on the shading, I was never able to figure out how to draw hair with a pencil (or perhaps I was never able to figure out how to draw hair ) but you capture the natural folds and locks of MJ's hair well. On the hair note: Peter IS hanging upside and unless his hair is gelled, I would think that more of his hair would be falling down versus what is currently lopsided. His hair doesn't have to be pointing towards the ground, but a few misplaced tufts on the sides of his head would complete his pose.
Excellent work, I will have to pick up the novel when I get a chance. Please let me know if this piece was supposed to colored or worked on more. Thanks!