The Colombia Single Origin is delicious. Its billed as a medium roast, so you don't get the sourness you sometimes find in a light roast, but it's not quite as intense as the Reserve espresso blend. It has a nutty flavour and hints of a dark chocolate. Doesn't have a massive aroma, and it doesn't leave a huge long aftertaste, but it's really good either as a straight espresso to perk you up in the morning, or in a long milky coffee if you want something to savour for a bit longer.
I always order a mixture of different pods, and this one is always included.