I put one on my back door for our german shepherd. The idea is great but two issues I have that would discourage me from buying another is.
1. There are two swinging parts to the door so when the dog goes out or in, these to pieces clack together and it is really LOUD so depending on where your bedroom is and how often your dog goes in and out at night, it can be miserable.
2. The dog has to be square in front of the door and pause for it to get the signal from the collar. I had to stop using that part because my dog would try to go through and if it had not unlocked fast enough, he would just bark for someone to let him out if he really had to "go".
I must say in fairness that I got mine early last year and it is very possible that the design and technology could have improved so do not take my thoughts as a reason to not investigate the product but do some tests out of the box before you actually install. It was my first one so I never even thought about doing some testing before I cut the giant hole in my door.

P.S. Robb, thanks to you and all your gests on the price podcast. I have listened to all of your shows and many more than once but that pricing podcast is one I will listen to many many times. You personally gave information about armadillos from your experience and I am currently getting my butt kicked on a armadillo job because of my poor pricing decision.....but it will be the last time. (hopefully)

Sincerely
Richard Waite