Even boot2docker (docker machines predecessor) could do that. It shared the folders correctly and managed port forwarding. Of course localhost stop working but I just added the ip in /etc/hosts and enter docker.local instead (the docks say the IP might change but that's never happened to me).
Except on Mac, where it sometimes doesn't. Have you not run into permissions issues? Or having a file-watcher process running in the container not being triggered by changes from the host? There are a tonne of quirks that came with boot2docker. It was worth it, of course, but they were still there; and this app is specifically aiming to address them.
