This is something that I've been thinking about a lot over the past couple weeks.
I've been on Goodreads since 2008. Before that, I used the VisualBookshelf app on Facebook. It didn't really work for me though because I read a lot of obscure or esoteric titles and many of the books I've read weren't in the database.
When I first joined Goodreads it was really small. Nobody posted gifs in their reviews, and I would see pretty much the same people over and over again, posting reviews in their specific genre.

That feels so long ago now!
I didn't really become a popular reviewer until 2011. I posted under the name Pikachu Ketchum (which is why some of my older friends still call me Pikachu), and for the first time I broke the top reviewers' list. I had a following of people who were really friendly and shared my quirky sense of humor, and respected me for always posting an honest opinion of the books I read. In late 2012 I started publishing novels under the name Nenia Campbell. I also started my modestly successful reviewing blog,
The Armchair Librarian where I posted reviews of the ARCs I received, both from authors themselves and also from Netgalley.
When people take issue with me—as is inevitable on any online venue—it's usually for one of several reasons, and one of the main ones is that people think it is hypocritical of me to post reviews as an author. Which I totally get. "Your books are shit, Nenia. How dare you give that author a 1-star review! Your books are even worse!"
I don't weigh authors' books against mine when I'm reviewing. I know what I like. I like books that are well-written, that feature interesting and complicated characters. I like plots that make me think about the world in a different way, whether it's some frightening glimpse of the future or an insider's look at some under-reported subculture or a heartbreaking (or not-so-heartbreaking) love story with LGBTQIA themes. I like books, basically, that don't make me feel like I've wasted my time and my money.
I reviewed books for four years before I became a published author. A lot of the friends on my friends list are friends with me because they like my reviews. When I first started publishing, I made a promise that I would keep reviewing as I wrote books, and that I wouldn't change my reviewing methods just to ingratiate myself with others.
I won't lie and say that it's not hard. I lose friends pretty much every time I post a negative review of a popular book. Sometimes if someone doesn't agree with one of my reviews, they decide to revenge-rate all my books. Or harass me with sock puppets. I don't get nearly as much crap as some of the more popular reviewers on this site do, but I do get some, and sometimes it's crushing.
Maybe if I only posted positive reviews I wouldn't have this problem, but reviewing is such an integral part of my life. I love the feeling of reading a really good book and sharing it with others. My 1 star reviews can be harsh, but I think it's important to be honest. I love knowing that people actually trust my opinion, and know that when I give a book 5 stars it's because I genuinely loved it and not because I'm trying to buy my way into someone's good favor.
Thank you! I feel the same way. It really makes me wish I could read minds, because I would love to see what makes people love the books I hate.