If there is a characterization or plot problem, simply point it out and explain why you had a problem with it. It is of no value to simply say you like or dislike something. We need to know why so we can do it again or avoid the pitfall later. If you don't like something, try to determine why. Also be specific about your favorite scenes, lines and descriptions.
Feedback can be uncomfortable at times.
Some of us can deal with it better than others. Work at making your comments useful.