I have three of these nest boxes and have given two as gifts. My Swedish Flower Hens, Easter Eggers, and Legbars really like these. My Swedes and Easter Eggers like them so much, they were fighting over who got to use the box so I installed a second one in that run. They do try to fit two at a time in there when I first let them out of the coop into the run where the boxes are hung. Inside their coop they have four spacious wooden nest boxes but they still want to wait to use the bucket nest box. If they break an egg jockeying for position in there, it's easy to clean the bucket: just rotate the opening 180% so that the perch is upside down and you can clean them out easily enough. If there's a bigger mess, it is not difficult to remove the bucket lid and do a clean sweep with a sponge or rinse them out in place. I bought the kits (bucket, mounting hardware, and perch) so I cannot speak to the ease of lid removal if you supplied your own bucket.
I do have mine set pretty high off of the ground, but even when I had a ramp going up to one my Jersey Giants and Wheaten Marans would not use them. They're just too big a bodied bird to fit inside. If you have Exhibition-type Rhode Island Reds, Barred Rocks, Brahmas, or any of the other larger Large Fowl I doubt these would work for you.
Cons - hard to install with a gun type cordless drill. Don't beleive them when they claim works for large fowl.
I am now the proud owner of 6 fowl stuff nest boxes that none of my hens can get into. Tried putting one in the box and she fit barely but could not turn around in the box and she ended up backing back out of the box. Not sure if I can modify the fronts to fit something else or not. Would NOT buy again, Based on this next box assuming that the one they market for bantams might work for a pigeon. Great idea BAD BAD BAD BAD for real chickens.