Why haven't femtocells taken off as planned?

The notion of providing customers with their own miniature base station should have been an easy sell for the developers of femtocells. Operators adopting the technology could improve a user's mobile phone reception and boost the customer experience--critical to attracting and retaining subscribers. While femtocells offer a simple proposition, persuading operators to deploy the devices has taken significantly longer than even the most conservative estimates. Why haven't femtocells taken off as expected, and how will femtocells fit into the evolving network architecture landscape? Special feature