The iPad Mini with cellular modem has fast 4G compatibility. Time for a test at the International Airport of Amsterdam - The Netherlands. Have a look;
4G LTE speed on the iPad Mini
4G cellular networks are slowly being rolled out across big cities, here is a 4G speed test at Schiphol International airport in the Netherlands in February 2014;
Connected to T-mobile in the Netherlands using a prepaid simcard, the 4G download speed at this location averaged between 75 and 87 Kbyte / sec.That's a disappointing 0.679 Mbps
4G LTE with VPN encryption
On the same location with a VPN encryption tunnel enabled located at Amsterdam, the 4G speed dropped a bit;
The average speed with VPN enabled on the same location dropped to 56 Kbyte/sec.(0.437 Mbps)
4G LTE speed test results
The test results with 4G internet connectivity;
The 4G internet speed was expected to be much higher. However, Schiphol International Airport is a very busy location with lots of people carrying smartphones, tablets and laptops.
Although 4G is advertised, it doesn't necessarily mean a higher speed on busy places.