Private WiFi is a $10-per-month ($85 per year) service that secures your data from Wi-Fi hacking by placing it within a VPN (Virtual Private Network). It does this with client software (PC and Mac) that connects to the company's own secure servers.
The Private WiFi client software installed on your local PC is a version of the open source OpenVPN. Once installed, you may active or deactivate the VPN (the secure connection). Private WiFi's value is in providing the server at the other end of the connection to complete the VPN tunnel. Everything going to and from your PC is encrypted until it reaches this server.
Of course, data could be intercepted between the Private WiFi server and its destination, but that's supremely unlikely--and there's not a darn thing you can do about it. What most users should be worried about is someone intercepting their Wi-Fi signal in the coffee shop. Private WiFi won't stop that, but it will assure that the interceptor can't decipher it. The program uses its own encryption so it will even protect those that do something stupid like tape their password to the laptop. Don't laugh--I've seen it.
I noticed no performance drop-off using Private WiFi. I'm in San Francisco and the Private WiFi server I used was in Los Angeles. This doesn't mean you won't experience any performance drop-off, but there are other servers in Amsterdam, Missouri, New Jersey, New York, Singapore, Toronto, and Virginia, so you should never be too far from something viable. The software will pick the nearest server for you automatically if you wish.
The likelihood of anyone actually stealing your data in the local coffee shop is pretty darn low. And of course, if your data is mundane, there's no reason to worry about it. That said, if you must deal with sensitive data and don't have a company VPN, then Private Wi-Fi will do the job.