saxony was my puppet, I needed their armies. They were always in place to attack armies from France who penetrated deep into German soil!I think you would have continued trouble with Britain and France (and maybe Russia) if the game was still continuing, but given that it's all over, you can certainly say you did a good job. Prussia is vastly stronger than at the beginning of the game, Austria is mostly intact, France is a little weakened and Britain is absolutely humiliated with your occupation of its northern shores.
In real life, there is no way it would last, but for now, you have a pretty map of Prussia. Just a shame you couldn't annex Saxony, and connect to your pockets deep in Russia, as that would really smooth out your borders.