You can find our public roadmap here:
The roadmap gives you a general idea of some of the bigger features we have planned and how we prioritize them.
The roadmap is by no means complete. There are many features we have planned that are not on there and new feature ideas come up all the time either from our users or by us.
The roadmap frequently changes as we adjust our priorities based on what users tell us is important to them. So don't be shy and let us know what you want to see in Marvin! :)