Sprint's Overdrive hub is a lot more than a cellular modem: It's got dual 4G/3G connectivity, shared connections with up to five devices over Wi-Fi, and can serve as a sort of mini NAS, with shared microSD storage.
Early leaks of the device were mostly right, but given that the Wi-Fi range is even further than expected—150ft, Sprint and Sierra claim—actually undersold it a bit. (WiMax is fast enough, and that Wi-Fi range is long enough, that you could conceivably use one of these as your primary source of internet at home. Nuts, basically.) A 1.4-inch LCD screen lets you know who's connected to what and how, and gives you a precise battery reading—fixing one of the dumbest problems with Verizon's Mifi. Actually, all around this device feels like the MiFi on steroids—it's even a bit bigger, at about 3 x 3 x .6 inches, though that's still pretty compact for what you're getting here.