I still can't believe the size of this thing. It's giant! But it's also a really nice addition. We have the Big House 4, which has plenty of room for 2 of us inside. However, we also just got a puppy, who's still new to camping. We have to pack her kennel to ensure that she doesn't wander at night, and it's really nice to have the vestibule for her. We can put her kennel on the far side, and still have plenty of room to access the vestibule and tent doors (and I promise you, this kennel is sizeable, she's a newfoundland!). I love that it has two doors, and is very easy to get set up. The first time was a bit confusing, the directions were only so helpful. But once you do it once or twice, the vestibule can be put up super quick, especially with two people.
I would definitely recommend if you're looking for some added space on a Big House!