Back in the days my friend had a motion detector (which just compared with previous input) on his webcam which would write the pictures which were served over Apache. He'd use this to figure out who entered his room (attic), and what they did there. Until one day his mother cleaned his room, the camera got pointed upward to the top window, and it was weirdly cloudy with clear sky in between. That day his harddisk got full.

Looking at the input devices for data:

    Accelerometer: phone’s motion and vibration
    Camera: motion in the phone’s visible surroundings from front or back camera
    Microphone: noises in the enviroment
    Light: change in light from ambient light sensor
    Power: detect device being unplugged or power loss

This is a bit more advanced. It can warn when it loses function, power, or is unplugged. It can also be self-aware that its being moved or touched.

A Raspberry Pi can have a camera module and one can easily script the power loss capacity. You can plug in a microphone on the USB. Light sensor is sortof within the camera, just requires constant stream. Accelerometer is just a bonus on top of camera. You'd see the device moved via camera as well.

I see a few problems running this in a hotel room: its gonna need 24/7 connection. WiFi captive portals (common in hotels) usually time out after a while so you might prefer a SIM card, or either. Both would require something like a VPN or SNT. The data shouldn't be that much. Problem is, what if these networks aren't available? The power is essentially paid for, and not that much, but running this 24/7 is going to have impact on the battery life of your phone.

For me, this would be useful for another reason: cause we got a paid cat caretaker when we're not around.