Interesting product, Kathleen. I'm only familiar with T-Mo's Hotspot @ Home, which is basically Wi-Fi calling (I think), but the Airave apparently creates a full-fledged CDMA "bubble" in a 5,000-square-foot area. Everything I've read about it says the performance is really great - sounds like you're going to be very pleased, especially with the costs waived!
The only caveat I encountered was that when the Airave arrives, it's set up to allow ANY Sprint phone within range to log on and make calls - the phone user doesn't have to take any action: it's as if you've just walked into a regular coverage area. You have to talk to Sprint customer service if you want to restrict use to only the phones that you own or approve. Probably won't be a big dea, but if you're concerned about a lot of foot traffic or a public area near your house, you might consider asking Sprint about this. Apparently, each connected phone will use some of your broadband capacity, so in theory this could be a problem.
Also, while not a big concern, apparently the Airave requires a GPS lock in order to work - there's an internal receiver that needs to lock onto GPS satellites so Sprint will know you're using the device in an approved area (for example, in the US, instead of overseas). You should be able to get a clear view of the sky with the Airave, but if you're deep in an urban area or under lots of tall trees, you might have to fiddle with positioning the device to get the GPS to lock on.