My husband had used Kiwi for his house before we were married and called them back to clean some of his rooms when he was ready to the sell the place. I met them at the house and they did an ok job, but it wasn't that great. Plus, I wouldn't have characterized the smell that remained as a "great scent"... I was going to post that they leave a chemical smell in your house that I found very unpleasant and then I read the other post about the "great scent" so I guess it's a personal thing. I've used Zero Rez several times (both at my house and now at our new house) and I found that they leave things just smelling clean, but they don't have the $4 deal for repeats... in fact, I haven't called them out within a year, so I don't know what kind of deal they would give for that sort of thing.
Oh, and there is a service call charge along with the $4 per room. It's been almost two years now since my husband sold his old house, and I can't remember how much the charge was, but it was significant... I know he had 5 rooms and a halway done and it was almost a $80... that seems like a lot more than $4 a room to me! (he did have one room that had spots treated and that was extra, too, but still... it was a lot more than we were expecting with the advertised $4/room deal!).
With two dogs, a toddler and husband, I've just about given up on clean carpets for now! :-)
P.