There's not a thing wrong with it. All the fabrics go well together and I like the pattern. With that said, I think perhaps a couple things are going on that make you not love it. Some others have mentioned similar things:
1. The color combo is "almost but not quite" Christmasy because the yellow is a tad pale. It could look a bit washed out compared to the more saturated reds and greens there.
2. Instead of a stop border being solid, the motion of the quilt continues with a highly patterned border, so maybe it's lacking a sense of rest to the eyes?
3. In the picture, it is very near the plaid sofa which has similar but richer colors and a different look altogether? Have you hung it elsewhere or laid it on your bed to see if it looks better to you in a different setting?
4. You've just looked at it too long. That happens.
Once you can put your finger on what is troubling you about it, you'll know for next time. Make someone really happy by donating it--and then find a new quilt to dive into !