If You Read Reviews:
If it is a negative review: Every author gets a negative review. You're not the only one so don't let yourself get down! Getting a negative review might help to point out things that you did wrong. Maybe someone pointed out a plot hole, or a few other things, either way, you'll be more cautious to take notice to such things with your next novel. Negative reviews aren't all bad.
Don't ever contact the reviewer to harass them, or explain why their review is wrong, and why your book is actually great! Don't be a rude author! Take feedback with grace. Feedback, whether good or bad, still brings attention to your book.
If it is a positive review: I'm pretty sure reading a good review makes every author swell with pride. Should you comment or write this person about their review? You can if you want to say, "Thank you" but maybe don't praise them--it could make the reviewer uncomfortable. But sending a generic "thank you" email or comment should be okay, it just depends on the person.
If You Don't Read Reviews:
If you don't read reviews on your book, you'll never know if someone said a good or bad thing about your work. This isn't necessarily a good or bad thing; like I said, it depends on the person! By not reading reviews, you won't know what needed to be fixed, and you could make the same or a similar mistake in your next novel.