When the DXO One first came out I didn't really see the point of it. Seemed a bit unwieldy to attach it to a phone to take pictures. I pretty much ignored the camera since then.
Turns out DXO added a couple of interesting features into the camera over time including the ability to use it standalone. In standalone mode this camera is *tiny.* It makes a Rollei 35 look big.
Body upright like that gives the standard 3:2 landscape orientation. The camera has a 1" sensor (like the RX100 II) and has a fixed focal length f1.8 lens with an equivalent of a 32mm FOV and it shoots RAW.
The 1" sensor means lots of DOF. And that is where the camera gets very interesting. In standalone mode the camera basically remembers the last settings you put in while it was attached to the phone. It has the normal PASM settings as well as auto focus and manual focus. AF is a little slow and deliberate. Manual focus an additional option of a hyperfocal setting where the camera will move to hyperfocal for whatever F stop it is shooting at. All of these settings are saved in the camera when it is disconnected from a phone (and it retains them through power cycles).
You can set the camera to aperture priority, auto ISO, put it in MF hyperfocal (or any MF distance you want) and disconnect it from the phone and the camera becomes a tiny little snapshot shooter.
When disconnected from a phone it has very few options that can be changed. They are adjusted using the touch screen OLED display. You can move from stored settings to Auto Mode (with AF), Movie mode and can go back to the stored settings.
Framing is interesting. The OLED display is B&W only, no gray scale at all. But it actually works as a way to frame a shot in a weird pixelated way. No chimping, previewing exposure or any of that available.
Turning the camera on/off is by the sliding cover in front of the lens. Takes about a second to be ready to shoot and it remembers whatever mode you were in when you closed the cover.
Only take a few shots so far but quality looks good for such a tiny camera. It is about as unobtrusive of a decent camera as I have seen. Deeper than a Minox B but not as long. Build quality is good, metal body that feels pretty solid.
No idea on battery life yet. MF mode will help. Built in battery that is recharged by USB so a battery pack can work with it. Micro SD for storage.
DXO discontinued them a few months back and they can now be found for much lower prices. A seller on Amazon has what I think is the original version for around $130. I had $50 in credit so it was about $80.