Are eBook Proofreading Services Worth It?

I’ve been considering ebook proofreading services for my digital book, but I’m unsure if they’re really necessary. Can these services significantly improve the quality and readability of an eBook, or are they mostly helpful for catching minor typos? For authors self publishing online, do professional proofreading services make a noticeable difference in reviews and audience perception? I’d love to hear experiences from those who have used eBook proofreading services was it worth the investment?