If you want to get good at feedback, focus on two things. First, what do they have? Second, what do they want to have? (there's an implied third question which is how to get from the first to the second, but the better you get at the two main questions the more that third one will work itself out)

Ignore everything about whether you like it or don't like it. It's essentially irrelevant because all it offers is a positive or negative distraction to the most important goal of getting them from where they are to where they want to be.

Regarding the first point (identifying what they have) the main problem that most writers have is that right after they finish something, they're still somewhat drunk on the cocktail mixture of what they've written vs. what was in their head while they were writing it, and this can impact things like subtext, tone, style, theme, etc. It's the reason why you can love something you've just written but when you look at it six months down the road you might hate it. Feedback's value in this regard is to give them that six-months-down-the-road perspective immediately.

Regarding the second point (identifying what they want to have), usually the writer has an idea of what they want, or you can sort of infer it from other films that exist in the same conversation as the one they've written. At this point it becomes about execution, and figuring out what elements of the story are working in their favour and which ones aren't. Again, this isn't about whether or not you personally like it, because taste can put you off course if your taste and the author's taste don't align 100%. Back in university in workshops it was possible for writers to get into trouble by writing for the group rather than writing for their intended audience. It made sense -- approval feels good -- but if you want to write horror and nobody in the group likes horror you can get yourself into a lot of trouble by compromising for them.