Some writers may want to have their manuscript critiqued, once, at some point before they submit it for publication. Others join critique groups to share their wip during the long journey from concept to submission.
One critique or many can either help or hurt; it depends on you. The same goes for your published book; it can be received with love or rejection. Again, how it affects you depends on you.
Get your ego out of the way! Look at why you were given a negative critique and if no reason was specified, ask for one. This will help you with revisions to your yet-to-be-completed manuscript. If the person doing the critique cannot offer a reason then that person should do something else with their time and not waste yours.
Book reviews can also be good or harsh; it goes with the program. You will not be able to please everyone so don’t try to! If you are happy with the finished product, then you have done your job.
Some reviews are helpful, others may come from writers who failed to reach their goals. Again, take your ego out of it, look at the lessons to be learned from anything negative and use them to help you with your work. If you allow the negative to gain control, it will keep you from reaching the goals you have set.
Enjoy the rest of your day and, Happy Halloween!