Product review (3 stars): Not bad for the low price.
This unit is really designed to be mounted through a panel.  It will snap into a rectangular hole in a control panel or box, etc.  Used that way, it would make for a reasonably "Clean" installation.  But you would need to get inside the box or behind the panel to swap out the batteries when necessary.

It's not really designed to be used "free standing", but if you don't care how it looks, and don't mind that it's not really what you'd think of as a complete finished product, it does the job.

I have not used the thing long enough to know how long a set of batteries will last, either.  And that brings up another point.  Since this unit requires two of the little button cells to operate, it'll probably cost as much as the thermometer originally cost just to replace them if you buy "good ones" at retail.  Not to complain, though, because the gadget is very inexpensive to begin with.

I tested mine at the ice point of water, and found it to read 1.3 degrees C too high (reads 1.3 when it should be reading 0.0).  I also tested it at around 50 degrees C, and found it to read about 1 degree C too low at that point.

This isn't horrible accuracy for an inexpensive thermometer, but could be better with a bit of adjustment.

Opening the unit up, there are solder pads on the circuit board that will allow you to switch it to read out in Fahrenheit.  Another pad looks like it may be used to speed up the rate of update.  However, the battery life is probably shortened if you do choose the faster update rate.

There are also two surface mount resistors on the board, and it may be that the unit could be calibrated by adjusting the values for those resistors.  I may try that at some point, and report back if it works.  It would be nice to be able to set the offset and gain to get better accuracy, but for the price I paid, this unit will tell me if my freezer is functioning within reason.

Knowing that the ice point is off by 1.3 degrees (on mine), and that the slope is not correct, I understand what to expect.  Measuring the temperature of a refrigerator or freezer is a tricky proposition anyhow because they cycle on and off, and the actual temperature varies by as much as 10 degrees C in a typical home freezer anyhow.  So the reading will depend on what part of the cycle you happen to catch when you check the reading.

But the cable to the sensor is thin enough that you can run it in through the door seal and make your readings without opening the door to the fridge or freezer, and that's what I wanted.

The sensor responds fairly quickly.  For scientific use, refrigerator thermometers usually employ a small vial of a liquid to "damp out" the response speed of the thermometer.  That way, you'd have some hope of opening the fridge door and making your reading before the temperature went up very far.  Even with a thermometer like this, where you can make your readings without opening the door, the reading will depend greatly on when, in the cycle, you happen to catch the reading.  To that end, you may want to do something to slow down the response speed so that you see more of an average value whenever you check.

Slowing the response speed of a sensor is a bit more complicated than one usually thinks.  Most people assume that just placing the sensor into a larger container of water or the like will slow down the response.  But, interestingly, the speed of thermal response of an object is dependent on the ratio of surface area to heat capacity, rather than simply the size.

So, for example, a gallon jug of water will have the exact same speed of response as a quart jug of the same shape.  This is because the surface area to mass ratio is the same for both containers.

So what you really want to do, to slow down a temperature sensor, is to increase the thermal capacity AND insulate it to some extent to achieve the thermal response time you want.  You should also consider the self-heating of the sensor, and not simply insulate a tiny sensor.  Doing so may cause it to read artificially high because of the power being dissipated by the sensor itself.  In this case, the system is very low power, and the sensor is likely being read only intermittently, and briefly, so the power it will dissipate will be very low.  Still, it's worth keeping in mind that you will need some surface area on the final sensor assembly to assure that self-heating doesn't cause errors.

These sensors appear to be sealed, and may be waterproof.  So for a fridge, you could simply place the probe into a small semi-insulated container of water to slow it down.  But the container should be sealed, or at least fairly tightly closed, because evaporation of the water will cool the water below the ambient temperature.  To get an accurate reading you don't want the water to be evaporating.

I prefer using an aluminum mass, insulated to get the thermal time constant that I want, because it's easier to deal with in the long run.  But again, this thermometer is not super accurate anyhow, so I doubt most people will want to go to that kind of trouble.

Just keep in mind that fridges and freezers cycle on and off, and the temperature inside cycles up and down.  So if you don't do something to account for that, what you see at a glance may not be representative of the real average temperature.