We all get bad reviews. Some are very constructive and make our writing better. Others, we just sort of scratch our heads and wonder why the person bought a book so clearly outside their enjoyed genre.
One thing that I do, is look at bad reviews of extremely successful authors, such as Patrick Rothfuss.
I actually first heard of Patrick on Acquisitions Incorporated, and picked up his book based upon his Viari character. Seriously, I had no idea who he was.
Anyway, apparently he's one of the more successful and talented writers out there. Who knew?
My point, is that if you look on Goodreads there is this well written, scathing review on there. Pick an author, someone hates them.
Now, if ALL of your reviews are low... that's different advice that I'll write later. But for now, let's assume that you're at least a 3.5/5 average rating, and you're focusing on a few negative reviews.
The only ones that hurt are the ones we think are true, and thus, should learn from.
Think about it, if someone makes fun of your purple hair and you have green hair, it doesn't really bug you, right? The only time a negative review stings is when we see a kernel of truth within it.
So, route it out, and apply that wisdom to the next book. (hell, in the beauty that is the kindle era, you could go back and edit the previous book too, if the feedback was good enough)
The point is, EVERYONE gets bad feedback. Even literary geniuses like Rothfuss (who, if my editor is anyone to go by, has quite a growing community of angry people after him for book 3... as I just read book 2, I'm not in that boat just yet. Maybe next year ;)