I have a couple of them, and hooked up to my Herpstats, they do an excellent job of maintaining temperatures in a narrow range and holding in humidity. It may be necessary to add water only once during incubation.

However: You must put the vermiculite and eggs directly into the unit, you cannot use a secondary container. This is because the units are just too short.

They can hold only about 2 clutches of ball python eggs.

You must be vigilant when babies hatch, or they can crawl up into the heating elements. I haven't had any harmed by this, but it can be a pain to get them out.

I put my more valuable clutches in these, rather than in a larger incubator, because they are more stable and I can monitor them more closely.

Assuming you didn't get one that is defective from the outset (rare, but can happen with any such device), they are extremely reliable. Do not use the wafer thermostats--they can work, but they are simple analog thermostats and the temperatures will not be as stable. They also take forever to set up properly, and would have to be readjusted if the ambient temperatures changed. It's not worth the risks.