Most of us have at least one part of ourselves that we just do not like. We are often ashamed of some part of ourselves for one reason or another. "God, why did you make me so quiet? Why didn't you make me an extravert?" Just remember that no part of you is a mistake. Whether that is physically or characteristically. You are just the way God made you to be.
However, that doesn't mean you can't/shouldn't change. Maybe God gave you a temper so that you would have to learn to control yourself. Maybe God made to you have physical issues so that you could conquer them or learn to deal with them and become a stronger person and be an inspiration to others to do the same. Maybe God made you who you are now so that you will become someone else later on.
You don't have to LOVE every part of yourself. But instead at looking at the flaws you have and beating yourself up about it, look at your flaws and see them as ways you could improve yourself. See them as a inspiration, not a discouragement. God would not want you to hate on His creation: you.
On the other hand, God also has given you special gifts. Whether you are good at organization and leadership or you are creatively expressive. Even if you can't think of any gift of your own, don't be discouraged. Some gifts are not obvious to the normal eye. You could be very caring or very determined or even good at inspiring others and not even realize it.
Every gift you have been given is given to you for a reason. It is up to you to use them.
You may look in the mirror and think "Wow. What a mess". But that "mess" is nothing to be ashamed of. The messiest people make the biggest redemption stories. You have all the pieces of the puzzle, just because they may be jumbled up doesn't mean you can't create the beautiful picture that they can make. That beautiful picture will be you.
So don't look at who you are now and be discouraged. Look at yourself and be inspired because God has made you special. You have yet to fulfill your full potential, so don't just be "satisfied" with where you are now. Instead push towards the person God wants you to become.