In technical terms it's a femtocell, yes. But if they're handing out femtocells that themselves connect over the cellular network that users can just dump on a windowsill to improve their signal with no configuration, that's somewhat interesting, and different than how carriers have been deploying femtocells until now.

femtocells require a local broadband connection to create the connection to the cellular network. This is just a repeater for towers within a certain distance. Requires no connection to broadband for the customer.

Which is to say if there is no sprint tower near you this is a useless product.