In other words, would you rather have an honest review that may have something in it that you may not like hearing (but could help you improve), or a review that might be filled with lies just to give you an 'ego-boost'?
Well, we see a variety of both of these types of comments here at StoryWrite. And while there is nothing wrong with either, I think it's only fitting to hear about both types and weigh the options for your own future comments(whether giving or receiving).
Honest Reviews:
In an honest review, the reader will comment with their impressions on the item. It could include constructive criticism, suggestions, and other improvement techniques. Some of these types of comments aren't always appreciated by the writers, though.
It is in my opinion that every person here who is truly serious about writing should welcome honest reviews with an open mind. They can help you improve and work toward mastering the craft (although, do we ever really 'master' it?). No matter how long you have been writing: whether it has been 20 years, or 20 days, we do all make our mistakes- and having precious readers to help us correct those are something to be appreciated and welcomed.
However, there is a fine line with honest, diplomatic comments, and insulting, harsh ones. So, for advice, be careful how you word yourself. Point out things that you like about the piece, offer criticism in a polite and friendly manner, and end your comment with your final thoughts. You should never insult a writer, or discourage the author in your comment (i.e. 'this was stupid', or 'you're a horrible writer'). If you truly didn't like what you read, just try saying something simple like, "I'm sorry, this just wasn't my style." or don't comment (unless you're having to comment for a contest or something along those lines).
Candy-Coat:
In a candy-coat/fluffy review, the reader could be lying to you. These type of comments generally don't say much other than "This was so good!" without offering any kind of criticism for improvement. Nine times out of ten, this type won't even tell you what they thought was good, and probably couldn't recall or discuss anything about your story with you. These comments also have been known as 'spam' comments and could get you in trouble if you're copying and pasting the same exact comment all the time.
Now, I'm not saying that all of your comments that are like this mean that you're being fed lies. In some instances, the reader may not know what else to really say, and really did like your item. I personally have come across many stories where I was just left with absolutely nothing to really offer, but I did still tell the people why I thought it was good and what I liked about it. 
But reality does need to be faced sometimes. Not everyone is going to like your writing. You're going to have critics (and if by chance you ever get published, be prepared for all kinds of criticism). So, as long as you keep that in mind, and your 'ego' tamed a little bit, you'll be fine. 
Take any comment you receive with appreciation. Thank your reader for taking their time to offer feedback (whether you were praised or not). After all, every author relies on the readers, and that is how we all improve. That is why many of us are here at StoryWrite. I thoroughly love any kind of reviews I get. 
Various people like various types of comments. If you're unsure of what type of comment to leave the author, try backreading their comments, and their responses to comments. Check the Author's Notes to see if they ask for a specific kind of feedback. And then just go from there.
Adding your comment:
Thankies for posting this! (It's time peeps got to see what's up!)
j/k I really loved it.
Oh, well. 
That was either straight up candy-coat, or spam 
