Authors pretty universally hate, fear, and loathe one-star reviews, which makes them humans, and creative people who identify with their stories. However, from the customer's perspective, A Funny Thing Happened On the Way to The Forum... I mean, one-click buy button. And that is, bad reviews help sell books.
You see, your customers are internet-savvy. They understand that if a thing looks too good to be true, it probably is. If you have a book that has 50 reviews, all five-star, you will have to work harder to sell the book than if you had 15 reviews, 4.2 out of 5 stars. The latter looks authentic, because we instinctively know there's one in every crowd that hates the thing everybody else loves.
Also, the tone and tenor of the one-star say as much about the reviewer as they do about the product. For example, a steamy contemporary romance getting a one-star "this was a wonderful love story, until the author ruined it by having her two characters engage in out-of-wedlock intercourse!" will sell far better to its target audience, because that's exactly what they're looking for. (That's a true review, by the way, and the sales lift was noticeable, though the author was torn between laughing on the way to the bank and crying over why, why, would a buyer think they were going to get anything else in that subgenre?)
I personally have dropped a hefty chunk of change for a cookbook on the strength of a one-star that said "This has almost no new recipes! It's just a collection of the best recipes from her five previous cookbooks!"
Closer to home: Peter's prison memoir, Walls, Wire, Bars and Souls
The first one star said "I have never been to prison, nor worked in a prison, so I guess I can't really say how I'd feel in his place, but when he discusses 'the criminal type' or personality, he sounds ...kind of disturbing. It made me uncomfortable."
This review did not hurt sales of the book one bit. In fact, it has chiefly functioned to make people who work in law enforcement gigglesnort, and people who are looking for a realistic view of the inside decide the book clearly isn't whitewashing the problems and dangers involved in working with rapists, murderers, pedophiles, terrorists, and drug lords.
Check your one and two-stars for technical issues (or if it hurts too much, have a friend check them). If they're complaining about formatting, you may need to strip the formatting and upload a cleaner version. If they're complaining about spelling (and you didn't write in Queen's english when they expected American english), make sure you ran a spellcheck on the final uploaded file, and then consider running a text-to-speech program to see if any homophones didn't get caught (or were created) by spellcheck. (For instance, did the heroine receive a "twelve carrot" diamond or a 12-carat diamond?) Robotic speech is good at catching homophones that are hidden by regional accent, as well as skipped and doubled words. (If you did write in Queen's English, a disclaimer at the front stating that it is written in British English, and spelling and grammar will vary from American, does a lot to cut down on the complaints. Won't eliminate them, though.)
If it's not a technical issue, a one-star or two-star review simply means this: the word of mouth, reach and discoverability of your book has now grown beyond just the pool of people who will like it (or like you). This is a good thing, because it means more and more people are hearing of your book. You're not shouting into the void; people are finding you.
It hurts, yes? Remember they're not attacking you; they're criticizing your product. The reviews are for other customers, not a direct conversation with the creator. As well, each reader brings their own emotional baggage and personal history to a book, and sometimes what they get out of it is very, very different than what you put in. Rant privately to friends, but do not engage the reviewer. (And if you must, keep it to the polite "Thank you for your review. I'm sorry you didn't find the book to your taste.")
Have a cup of what's good for what ails you, go look up your favorite story and read it's one-star reviews and commiserate that you're in good company. Then sigh, say it's likely to help sales, and keep on writing.
*Caveat: if it's the only review of a story, yes, it can sink the story. Sorry.