I'll be the odd man out and voice a little consern with the design.
I cant see what else is inside the holes but the welded jail bars and maybe the door latch present a hazard to some dogs. Ideally the entire interior should be smooth and free of protrusions.
An excited dog, maybe scratching and digging, can be injured on the exposed bits.
Thanks Breck went out and checked, bars are all rounded off and smooth along with the cut out area of diamond plate, door latch locks into square tubing only accesable part is the knob, the 3 dogs I have now , even the puppy on the right are pretty mellow in there box, not saying I won't have a scratcher or digger or have someone elses dog in there, but I don't see anything that would be a problem, but I'm glad you made me go out and give it a through inspection.