Great idea with undocumented extra features - and vulnerabilities.

Unfortunately Modern mobile devices are equipped often have limited storage capacity and interfaces. The propagated by the manufacturers as a solution cloud may tackle within reach of the domestic Internet access yet, but go there often lack sufficient data throughput and affordable rates.
The sheet-anchor USB OTG stands on many devices do not or only very limited available, is shaky, only allows a device to access and sucks the battery is empty, while the charging port is blocked.

Here the RAV FileHub steps into the breach by providing the contents of up to two storage media (SD card and USB) via Wi-Fi - a quasi mobile private cloud. A separate battery life to doing the cell phone battery and provide enough power even for USB hard drives.

Other pluses:
(+) Access to the data requires unlike many competitors no special app. Instead of FileHub generates normal SMB / CIFS shares that can be accessed with almost any file manager to.
(+) If times nothing can be installed or configured, the data access necessary even only through the web browser is possible.
(+) Direct copy (without going through WLAN) between the storage media, for example, to back up the photos from memory card to a USB stick.
(+) An integrated hotspot feature gets the Internet, while the mobile phone / tablet is connected to the FileHub.
(+) The battery can also be used as an emergency charger.
(+) Compact, travel-compatible design.
(+) Side CIFS also exists an undocumented WebDAV access [.....]
(+) Under the hood tinkers a fairly complete Linux system, which is accessible via telnet - a paradise for crafters!

Weaknesses:
(-) The battery capacity is very tight when used as a charger.
(-) The configuration software does only the bare necessities, many sensible options are missing. In particular, I miss a guest user, the only access explicitly shared files, but not the same read everything and especially can not change the configuration.
(-) The hotspot feature is not working at Internetugängen with upstream login page ("captive portal"). The FileHub detects an error during connection setup, even before you had the chance to enter their credentials.

Well, and then there's a very large hook, at least for the inexperienced user: The designers have made unfortunately little to worry about security!
The root access via telnet can not be disabled. The easy ergooglebare default password for this account is only with "insider knowledge" changeable, but not over the configuration interface. The WebDAV access seems not even stop with passwords before granting full access to the data resources. And to make matters worse are these gateways not just only inward (to the logged on FileHub devices) wide open, but are published openly in the Hotel-Fi when using the hotspot feature!

All this can indeed be solved with some fumbling on the root account, the normal user without deep knowledge of Linux without hacking ambitions but so hopelessly overwhelmed.

The bottom line:
- Five stars for the idea and Hardware
- Three stars for some Spartan Software
- Zero stars for safety