As writers, we all get criticism and reviews. Hopefully, these are constructive verses destructive but we have to take the good with the bad. What's the difference?
Constructive is when one describes what may be missing, should be altered, or suggests changes in a tactful way. For example: If the sentence structures are incorrect, constructive criticism would be to point out how they are incorrect and suggest a way to reword or fix the issue.
Destructive is when someone slams the writing without offering any why, how, or suggestions to fix the issue. It comes across as personal. It's as if the reviewer suddenly forgets that there's actually a person on the other end of the computer. For example: If the sentence structure is incorrect, destructive criticism would be to tell the creative soul to stop writing now and find a different profession. This does nothing but crush.
Within the writing field, it's easy to say 'just be blunt' but we must consider that every day is not going to produce pearls of wisdom or diamonds (even if their in the rough). Sometimes creativity takes time to emerge.
I've reviewed plenty of writing and read some posts that looked like they were written through someone's phone while they were horseback riding (not good). If offering feedback, look at the main theme along with the writing. Sometimes, the theme is great. Don't hesitate to let the writer know that their content has promise before tactfully explaining that the structure needs work.
If the content is all over the place, offer suggestions on how to pull it together. It could be that too many characters overtake the plot. Or the plot has holes, isn't believable, or is too dark. Whatever the case, remember there's a person at that keyboard who is attempting to relay an emotional message through their writing.