Well, having been bit quite aggressively by a large adult female, I can tell you it doesn't feel good... It's also not the most painful thing I've ever felt.

She got me between my thumb and first finger, with a full-on feeding response strike. She coiled my hand and wrist, and refused to let go for several minutes. Every time I'd twitch she'd tighten up. I ended up with a perfect set of marks, showing basically every tooth in her mouth. It's all healed now, but you can still see where it was.

As a comparison, it hurt less over all than any of my tattoo's, and far less than being tagged by the iguana I used to have. Just remember, if they bite don't jerk back because that'll cause more harm to your skin...