The first time you plug the device in it gives you a quick tutorial and asks you what temperature units you want:
It can't get much easier than that. Subsequent power-ons jump straight to that last screen there, showing its set temp, actual temp, and how long it has been running. The bottom line can be changed to a countdown timer as well.
The next step was to turn it on and start playing. I hung it over the edge of a 6-quart stockpot and added five liters of water at 18.3°C (groundwater temp here right now). I set the temperature to 50°C and turned it loose: it took 27 minutes to come to temperature. It overshot by 0.7°C before decaying back down to the set temp. According to my Thermapen, however, when the reading on the device was 50.0°C, the actual temperature of the water was 50.4°C. It held that temperature within 0.2°C while it was running, however, in an uninsulated stainless steel vessel sitting on a countertop (basically a worst-case scenario). It think the device is probably useful for most high-precision cooking provided that you check the temperature with a more accurate thermometer and compensate accordingly before adding your food.
The device itself it basically silent: the hum of the pump is very quiet, and is mostly covered up by the actual splashing of the circulated water. It does not appear to have a buzzer of any kind—it does not make a noise to indicate that the set temp has been reached, or that the countdown timer has finished, so I am assuming this means it does not have the means of doing so. I would strongly recommend to Duncan that future iterations of the board include a piezo device so that you can make a beep of some sort.
Physically the device requires that your water level run relatively close to the top edge of your cooking vessel, and there is not a great deal of margin to accommodate level changes when adding food. The best way to deal with this is to use a relatively wide, shallow cooking vessel, rather than a deep, narrow vessel, to minimize the water level change when adding the food (of course, then you will definitely want a lid of some kind to minimize evaporation). The pump is strong enough that in my standard stockpot the water is pretty close to the rim when it's running: I'd prefer a little more margin.
The countdown timer has a minimum five-minute granularity when being set: the minimum time you can set it for is five minutes and a maximum of 59 hours and 45 minutes. When the countdown timer reaches its conclusion the timer flashes on the screen for five seconds, and then begins counting up to tell you how far over you have gone (the pump does not stop running). It appears that it will only count up to the initial value of the timer: when I tested it I set it for five minutes, and when it had gone over time for five minutes, it reset to zero and started counting up again. I'd guess this is a software bug that has to do with how the device is checking for the timer completion, and is obviously very minor. However, in my opinion, without an audible beeper the timer is basically useless. In addition, it lacks sufficient granularity for cooks that last under 30 minutes (when a one-minute granularity is necessary, IMO), and cannot be set for longer than 59:45 so you can't do a 72 hour cook based on the built-in timer.
Finally, I killed the power externally to simulate a power failure: the device turned back on and remembered the set temperature, but not the cooking time or countdown timer. It did not turn the heater or pump back on when power was restored. If power failure is a concern you will want to take additional measures to deal with it.
My initial impression of the device is that even as it stands right now the SideKIC is worth the $175 it costs, when compared to the alternatives: it has some flaws, but if you have a decent thermometer and your own cooking timer most of them can be easily mitigated. I also think that with some very minor changes (some just software) it could be made an even better value. Obviously this is not a final verdict, since how well it holds up over time will clearly be important.