I'm self funding a Dexcom G5, not for lack of hypo awareness, but more for greater understanding of how various factors affect my levels over time.
My control is definitely better and my understanding is increasing. I love being able to stick my phone to the car windscreen and have near real-time feedback on my BG while driving or have it vibrate at a level of my chosing when I'm on my bike.
Down sides? Not on the NHS, and not cheap, but sensor life can be extended by simply restarting the sensor after the 7 day period and by sticking it down with Rocktape or Opsite Flexfit film. Also, having had mine 2 months now, I probably look at my readings too much and need to chill out a little.
With hindsight, maybe the Dexcom G4 would have been a better bet as the transmitters last longer and with an xDrip I could have used an Android phone instead of an iThingy, but I wouldn't be without one now.