It worked right of the box. I kept it set at its factory set temp at 77f. It didn't take long at all to stabilize the temp either. Great buy.
I ordered the E200 for my 40 gallon breeder after my other heater went on the fritz and so far I am loving it! (It is a bit long so if you have higher substrate in a 40 breeder be aware that you may have to adjust the substrate wherever you place it.) The temp adjustment control is probably the easiest to use out of all the heaters I have tried in the past. The biggest win for me has to be the mounting options; since I have a 3d background on my tank, it's great to be able to stick it on the side wall of the aquarium but be able to see it from the front. Still a bit early to tell but I'm sure this will be a heater I'll enjoy using for a long time.
Yes, I know it needs a lot of water flow, and it's better to know of a problem than to be oblivious, but the "LF" (i.e. Low Flow) indicator on this heater is annoying. After trying this one out, I went back to my old heater and will save this one for a forthcoming tank I'm putting together with faster water flow. Those with low flow tanks --e.g. based solely on sponge filters and/or with slow moving fish like kuhli loaches or bettas-- may wish to pass on this heater in favor of other options. That all said, it is a nice unit for a tank with good water flow. Aquarium Co-op service was fine and I love Cory's podcasts.
Ordered the E200 model for my 55g, which is located in my cold basement. The heater has been flawless in its performance and I love that I can easily glance over at the tank and read the temp.
I was looking for a heater with everything, and this one has it: a built in temperature gauge, covered & durable, alerts to dangers like too cold or hot, and is easy to read. I love that Cory recommended the heater so I know its good and it is. I got 3, I even put one in a very small tank at an angle and it has worked perfectly for a month, keeping my Betta and White Cloud minnows very toasty.