Yep, we have one and wouldn't be able to do without it. However, we learned the hard way that with our dogs (two Australian Cattle Dogs) that the door cannot give access to ALL of the house.

We called the dogs in from their fenced yard for dinnertime and they both came charging in to their kennels to get their dinner (feeding them in kennels makes for a less "grumbly" meal-time). Partway through the kitchen my male dropped something that looked like a large, gray mitten on the floor as he rushed to his kennel. I got the dogs settled and fed and turned to pick up whatever it was the dog dropped only to find a rather large opossum "grinning" and hissing at me in the middle of the kitchen floor! The dog's "plaything" was alive!! That, and the mud/sticks the dogs would drag in led us to make a few adjustments. We moved their door to the basement entry area.

We had the opportunity to put in a special area for the dogs when I designed the new house. The dog door that goes out into a dog run on the outside opens up to a small "dog lounge" on the inside. This area had a heavy, rubber floor and sturdy wall treatment (exterior cement board siding) so that it can be easily cleaned. The door to that area has a lock and deadbolt just like an exterior door so we won't have to worry about someone sneaking in when the dogs aren't outside (I'd love to see someone try when they ARE outside!). The lounge is small, but it's only there so that the dogs can have indoor/outdoor access when we aren't home. They're getting older and need to potty more frequently. That small lounge opens up into the "dog room" where I have a dog bath, grooming table, food storage and kennels. That way, when we come home if the dogs are a muddy mess we can clean them up before letting them back into the rest of the house. We just moved in on the 18th and so we're just starting to get things set up. I still need to get storage cabinets and the like in there, but the lounge itself is set up well enough to be used now. Eventually, we'll add a fold-up platform for the dogs to lounge on.

I would have loved to give them even more room, but the house is small (1200 sq. ft.) and we really restricted other areas of the house in order to arrange this space for them. Besides, they tend to lie in a pile together anyway and they seem pretty content with this space so far.