There may not be any mistakes in it -except bad fabric choices - but I don't like it when it is finished or near completion. I think I am just sick of it or it doesn't look as nice as the picture. After half a year or so in hibernation it looks much better or an idea comes to me on how to change it.

What everyone else said with one thing to add, wash it!
I always like my quilts so much better when I pull them out of the dryer and they are a little wrinkly and warm. mmmmm...

All of my quilts have mistakes. I always see them but no one else can. They told me this when I first learned and I didn't believe it. Over the years I have found it is true. Only you see your mistakes. I sometimes purposely will make a mistake or reverse a block! Why?? Cause no one is perfect and most certainly not me!! :)

My friend recently asked my opinion on a quilt she had just taken off the mid-arm, wanted to know if she should rip all the quilting out, I picked up the quilt, walked out the front door, called her to come out, told her to "take off running" down the sidewalk and se if it still looked bad to her!!! She just gave me THAT look, IMHO if she added anymore to it would have distracted from the original pattern. I definitely think we're too hard on ourselves.

It is a piece of art....YOU are not perfect...what you create will not be perfect.....we are human beings.....not machines....
Yes I get very angry with myself when I finish a quilt and see all the points that are not perfect, and the corners that do not meet, and some seams that are not super straight and maybe a fabric choice that was not exactly correct....but sewing that quilt filled my day, it gave me JOY, and the person you will give it to will NOT see those mistakes, they will be amazed at what you created and will see all the love inside the quilt.
Don't be so hard on yourself, this craft/art is a continually learning process

abc123 is right. You just need the perspective of time. My first ever quilt top (not yet quilted) looked awful to me, so I tucked it away in my closet. I took it out after months had passed and looked at it again. Seems I'd forgotten where the mistakes were and it looked pretty good.

Go to your local quilt shop, if you look at the quilts as intense as you look at your own you'll find mistakes, I do it all the time. Makes me feel so much better. I even went to a shop in lancaster, pa, quilts were over $1000 and I found flaws. thats a human factor, I was glad the flaws were there.

I'll agree with you ... I've often been very disappointed with the quality of some shop display and class samples. It gives me a good (or bad!) impression of the standards of the business at large. And an insight into how much belief and trust, I will put into any info they give to me. If taking a course, I want to take from someone that I can learn from ... not one I could teach. I'm not being smug with my thoughts here, just stating how what I see affects me.

I'm sure it's great

You are right. The quilts displayed at our local quilt shops are not perfect either. Thanks.