I come across this sentence : "I'm a long-time Dropbox user, but it's never been a perfect solution for me. Despite its developers' best efforts, Dropbox has never really gained complete integration with either my Mac or iOS workflow: It's always felt grafted on. I'm excited about iCloud Drive for exactly that reason — instead of a product, it really is a feature. And a useful one at that."
What is the author trying to express when he say "It's always felt grafted on"? Does he mean that he is not getting a perfect solution?