There's a video of Ira Glass floating around that I was sending to all of my friends a few years ago, on the nature of creativity and self-criticism.
One of the great points he made was that if you ever finish a project of any kind and think it's really great -- just perfect, and just what you wanted to achieve -- it's time to hang up your hat and go home, because you're done. You aren't going to improve from there, and you won't learn anything new (though there's always more to learn, in any field).
The harsh self-critique just means that your skills still don't measure up to your taste, and if you find yourself doing great without much trouble, that just means you have really poor taste.
One of the great points he made was that if you ever finish a project of any kind and think it's really great -- just perfect, and just what you wanted to achieve -- it's time to hang up your hat and go home, because you're done. You aren't going to improve from there, and you won't learn anything new (though there's always more to learn, in any field).
The harsh self-critique just means that your skills still don't measure up to your taste, and if you find yourself doing great without much trouble, that just means you have really poor taste.