Hi I'm Aaron, one of the GitBook co-founders checking in.
You are giving great feedback and I'm more than happy to answer any questions you have.
BTW, in case some of you missed it, we're a big believer in open-source, in fact our book format and toolchain is open: https://github.com/GitbookIO/gitbook
This allows us to build better publishing tools together, no vendor lock-in and developers can build plugins to extend GitBook's features, here's a few: http://plugins.gitbook.com/.
You are giving great feedback and I'm more than happy to answer any questions you have.
BTW, in case some of you missed it, we're a big believer in open-source, in fact our book format and toolchain is open: https://github.com/GitbookIO/gitbook
This allows us to build better publishing tools together, no vendor lock-in and developers can build plugins to extend GitBook's features, here's a few: http://plugins.gitbook.com/.