Remember to follow The Rule of 5 when hearing feedback on your creative work. I'm kind of tweaking the intent, but I'm sure you all have heard a similar rule.
When you hear less-than-flattering feedback, think this: will this feedback matter in 5 hours? So if it is something you disagree with or it really hurt your feelings, ask yourself if, in 5 hours, whether the comment will still be off base or still be bothering you. Yes? No?
Then ask yourself if the feedback will matter in 5 days. Same thing. Ask yourself if, in 5 days, whether the comment will still be off base or still be bothering you. Yes? No? A few days can take the edge off most comments and allow us time to reflect and consider what's been said.
5 months? Your ego will certainly have repaired itself 5 months later (hopefully). So consider if the feedback was really, truly off base. Often with a little time, we come around to see another's point of view. And then we can actually consider it.
Lastly, 5 years. Will you remember feeling bad over someone not liking one of your concepts or picking apart a layout or two? My guess is I highly doubt it. What we tend to remember 5 years later are all the positive things people say to us. All the things that help shape us into better people, better creatives. The not-so-good things, well, they may be hard to get over but they're certainly worth trying to forget.
Keeping a bit of perspective on the words and advice (and opinions) about your book surely helps. Take the good things to heart and give yourself time to take any worthwhile advice into consideration.