I would make sure I said thank you first. If I didn't like the colors, pattern, etc. I wouldn't use it on my bed but would find some place else to use it, spare bedroom, camper, a throw on the back of the couch in the familyroom. I definitely would make sure they giver knew what and where I'd be using it. The next time they came over I'd show them where I was using it. I know this is what I'd do because this is exactly what I did when I was given a quilt I didn't really like, but didn't really dislike.
My friend was very happy when she saw it laying across the back of the couch in the familyroom. I made sure I told her how much I appreciated it when it was cold and I had it to cozy up with.