I have both sizes, the EcoGlow20 and 50 models. They are foolproof EXCEPT they do not perform as effectively in really cold locations. Not that big a problem if you have quite a few chicks to huddle together under it. But I've used mine in the coop down to the high 20s. They work best around 40 degrees or above ambient temperature.
I love them! Better yet, the chicks love them.

. Snuggle under, snuggle at the edges when they don't need as much warmth, dash in and out from underneath them all the time, returning underneath to warm up again. No light shining on them at all, so there is a more natural diurnal cycle.
The only drawback I fins is that they're opaque so you can't see the babies when they are underneath 'em. Don't want to lift up the unit just to peek at the chicks (okay, I WANT to, but resist the urge).
Easy to clean, the 50 is much easier to adjust the height, and the power adapter cords are plenty long to set them up some distance from an outlet. The 50 has the longest cord.
I am never going back to heat lamps again!