I stop trusting Amazon reviews a long time ago. One of my favorites books of all times has negative reviews on Amazon but I read the book before I saw the reviews and was totally blown away by it. If I had skipped the book because of the reviews I would of not found a favorite author.
I find books given away for free are usually review by people who would not normally read them. This is a paranormal romance by the way so it probably follows the formula for romance not urban fantasy.
I actually bought the sequel now but have not read them yet. I have so many TBR books I am still trying to finish 5 books that I started in January.