I have not tried Kefir before so got the Marks and Spencers Kefir Raspberry to try.
As well as raspberry, there is a plain one.
According to Wiki:
Kefir is a fermented milk drink similar to a thin yogurt that is made from kefir grains, a specific type of mesophilic symbiotic culture. The drink originated in the North Caucasus, Eastern Europe and Russia,[3] where it is prepared by inoculating cow, goat, or sheep milk with kefir grains.
The raspberry Kefir was pinkish in colour and the consistency was slightly thick yet a bit runny.
As for the taste, it was really sour with a raspberry kick to it yet the sourness is different to Greek yoghurt.
I think would go well with a slice of cake to balance the sourness of the yoghurt!