We're our own worst critics! Many times after I've let a quilt sit overnight, I look at it the next morning and realize the quilting isn't nearly as bad as I thought it was.
How bad is the quilt - really? If the lines are a little crooked, that's no big deal. You say the flowers are distorted - are they really that bad? If the quilt is still square and lays pretty flat, I'd say go ahead and donate it. Picture a little girl getting that quilt - can she lay it on the floor or on her bed and smooth it out and is she smiling? If so, go for it. That's the kind of quilt that charities need.
If not - if the quilt just doesn't lay flat or is all catty-wampus - then reconsider its use. Those are the ones I cut up into smaller quilts and donate to the animal shelter for use in the kennels. Their residents need comfort too!