There are currently several ways of storing data in playfab and I feel none of them is particularly useful for games with complex data structure.
Catalog items are key/value pair. While Value can be stringified json it is not that useful. The only possible update here is all or nothing, while for example only single property in json changed.
Entity storage attached to title or player is nice but there are severe limits placed on it.
It would really go long way to have something like MongoDB exposed for users, which would allow to store more arbitrary data and manage it.
After some evaluation the lack of access for some more generic storage is the only thing that I miss in PlayFab.