Saying "good job" or "I liked it" when you didn't, may be the easiest thing to do, but I don't think that it is the most constructive thing to do or, depending on how close you are to a person, the most loyal thing to do. An empty compliment is usually seen through. Friends know when you're being honest, glib, or polite. I never press anyone to say anything about my work. First of all, if I am confident in it, I don't care whether someone likes it or not. Secondly, if the work has been compromised by other hands (often the case with movies I've written), I'll be first in line to throw bricks. But I figure if someone genuinely likes the work, it doesn't have to be coaxed out of them. If they didn't, I'm confident enough and thick-skinned enough to hear what they have to say, but I want opinions backed up with examples for why they hold that opinion and an in-depth discussion. They might actually say something that will resonate or help me grow as an artist or I might just simply disagree with them, but my feelings won't be hurt. I throw off easy, empty compliments when I don't like something, want to escape as quickly as I can, and don't know the person well enough to give them an honest thoughtful assessment.
The role of the artist is throw something out there and say: "This has importance for me, it resonates with me, it has meaning for me. Maybe it has for you too." Those who agree with you are your audience; those who don't,aren't.