Useful feedback describes your experience of the work rather than issuing a verdict. Say where your attention dropped, what you expected that did not arrive, and what you were unsure of. Point at the work, never the person. Offer diagnosis before prescription, and be specific enough that the note could not apply to anything else.
Flow diagram of 4 steps: Say what you understood it to be about, Say what worked, specifically, Say where you got lost or lost interest, Only then suggest anything.
"This is boring" is a verdict. "I stopped paying attention around the third paragraph and started skimming" is a report. The second is far more useful because it is falsifiable, located, and tells the writer where to look. It is also harder to argue with, because you are describing what happened to you rather than asserting a fact about the work.
The most valuable thing you have as a reader is your reaction, in sequence. Nobody else can supply that, and the author cannot see it because they cannot read their own work for the first time.
One sentence. If your summary does not match the author’s intent, that mismatch is the single most useful thing you will tell them, and everything else is secondary.
Not encouragement — information. "The detail about the closed shop made the stakes concrete" tells them what to keep. "Great job" does not.
Locate it. A paragraph number is worth more than a paragraph of explanation.
And frame suggestions as one option rather than the fix. The author knows constraints you do not.
This is not politeness for its own sake — it is precision. "You clearly did not research this" is a claim about someone’s character and unprovable from the text. "I could not tell where the figures came from" is about the work and immediately actionable. The second gets fixed; the first gets defended.
The same applies to tone. Bluntness is fine and often welcome. Contempt is not, and it reliably stops people hearing the accurate part of what you said.
Padding a real concern between two pieces of praise teaches people to distrust the praise and to brace for what is coming. Say the good things because they are true and useful, and say the concern plainly. Both land better unbundled.
If you are not the audience for something, your reaction is weak evidence, and saying so is more helpful than pretending otherwise. "I am not the reader for this, so take it lightly, but…" is a genuinely useful preface.
And if the work is finished and published, unsolicited restructuring advice costs the author something and buys them nothing. Feedback is most valuable when there is still time to use it.
Yes — when it arrives too late to act on, when it addresses a constraint the author cannot change, or when it is a verdict with no observation behind it. Accuracy is necessary but not sufficient for feedback to be useful.
Three substantive points is usually the practical ceiling. Beyond that people triage by what feels easiest rather than what matters most, so a long list quietly buries your important note among the minor ones.
Say that you skimmed, and where you started skimming — that is genuinely valuable information. What is not useful is skimming and then commenting as though you read it closely.