I'm STILL, with two modern devices that support Bluetooth+HS in hardware (iPhone 5, iPad 4) getting sub-megabit speeds when tethering via Bluetooth. Wifi tethering gives me full speed (about 20 megabits down, 12 up with LTE where I am). The hardware CAN DO IT! Why doesn't iOS use the full abilities of the hardware? Bluetooth tethering is super-convenient because it stays connected permanently as long as the devices are in range. If you're going to be tethering a tablet to a phone for a few hours it's much more reliable than WiFi. Apple fails.