Image Courtest of Grant Cochrane / FreeDigitalPhotos.net Yes, you are good enough.
You're going to through life with people setting their own standards up on you. Although they may thrash your confidence, you have to understand. What they're saying to you might not be true.
If someone is picking out your flaws because they're being nit picky and complaining about nonsense, don't listen to them. The chances are that they're not even happy with their own expectations. Just walk away and let them argue among themselves. It's a lot harder to continue and argue with yourself if nobody is there to counter it.
Perhaps it's something that should be looked at. If the person gives valid reasons about things that can be improved, try stepping into their shoes and look at their perspective. What might be defined not 'good enough' may not be the fact that it's not good enough, it may be the fact you and that person know that you both can do a lot better.
Some ways to feel better and reflect on your issues are:
Brain storm the problems, and what might be the root cause of them.
Make a decision based on how they're affecting and impacting your life.
Try using your own baby step solutions to implicating them into your life.
Finally, remember. As long as you're happy with who you are and what you do, people's input shouldn't matter so long you're happy.