I would shoot straight. Not once in my career have I ever suffered for an honest assessment given humbly. And you'll sleep better at night for it.
Same here. People also learn they can trust you to tell them the truth and help them figure out a solution.
However, I have a low tolerance for bad work environments so YMMV but if you can't be honest with people or trust them, you probably want to look for an exit.
Same. It is frightening how many comments point to the exact opposite, presumably with the ulterior motive that this increases the chance of self-preservation.
But at the same time nothing can be improved by this. Although a team should have exactly this as a goal: improvement of the product/service.
Your personal goal should be to satisfy whoever writes your performance review.
Obviously this doesn't apply in individual pursuits like swimming [edit] or in situations where the coach is beholden to other parties (a paying audience).
[edit] To clarify: A coach should incentivize things they believe win games. An athlete should do those things so that the coach gives them playtime. An athlete should also promote the fact that they are doing those things to the coach.
It's valuable to provide people with context when giving advice from personal experience. The person hearing the advice needs to understand how the situation you presented mirrors theirs and also have an idea of how similarly they are going to be perceived compared to how you were.