Really enjoyed this box - had hoped it was going to be easy enough to blitz through and get a good final rank but sadly stalled at the user stage.
Foothold: Classic web app techniques lead to some valuable info and red herrings, ignore the most obvious bits when you inevitably run into them and search for something else, which will require some less obvious info.
User: Enumeration, enumeration, enumeration, it will probably be obvious if you look hard enough
Root: You can now access some new info, I needed Google to tell me how to interpret the data that I needed though. Once I had this data, it was just a case of a classic root escalation technique.