Some writers like critique partners, some don't. I'm one of the former, and I'm fortunate that I've found two excellent critique partners.
Writing can be a lonely job, and it’s good to have a friend who is prepared to read your chapter and give you his/her honest opinion. The word honest is important. I don’t want just positive feedback with a few ‘nice’ comments, although a comment of ‘Great, this really worked well’ does wonders for your confidence. But at the same time, I want a genuine opinion and, if necessary, hard-hitting comments.
A good CP can help you to improve your story and your writing. They can highlight word or phrase repetition, overuse of passive verbs and adverbs, and showing instead of telling (I have been guilty of all of these but didn’t actually realise it until my CPs told me!). They can also look at the big picture and tell you what is working and what isn’t, where the plot holes or anomalies are and whether the pace of the story is too slow or too fast.
Sometimes (often?) we can get too close to our own story and characters. A critique partner comes to it with fresh eyes and can point out the things that you may have overlooked.
At the same time, it has to be said that every opinion is subjective, and that in the end the story is yours