This was my first year using on and its worked perfectly so far....once you get past the kinks. First, the actual temp (in the middle of the incubator) is about 3 degrees lower than the readout. It also seems to be a degree warmer near the very top and a degree lower in the very bottom because the fan only turns on when its actively heating. However (at least in mine) the temperature is VERY stable and the cooling feature probably saved at least one clutch when I forgot to turn on the AC before I left for the day.
Overall, I actually like this incubator once you get past the quirks.