I prefer the Turbocharger by REVV but the Afterburner is my second favorite, not as dark as Turbo but it's got a good depth to it. I find both of them to be very good using the strong button on my Keurig brewer.
Not bad, just not as caffeine loaded as one would expect from a name like afterburner. It's decent dark roast, but not as flavorful as a sumatran blend.