I haven't used them in years.
As I recall the flavor was rather...robust.
We ussualy would mix about 1 part cooked groats to 3 or 4 parts cooked rice or pearl cous cous to make it more interesting. I believe I served it on it's own once and no one touched it..
I grew up eating buckwheat groats, and still love them (it?). This stuff is also known as kasha, and comes whole, medium grind, and fine. I've mostly cooked the medium. I suppose the whole would work very well the way miahoyhoy describes (mixed with other grains), and the fine would make a porridge on the order of Wheatena.
I always use it as a side dish for meat, especially brisket that has been cooked with LOTS of onions and garlic. What I do is something like a pilaf (the directions are on the box of Wolf's Kasha):
Mix the dry groats with a beaten egg
Heat a pot, then add the groats/egg mixture (NO FAT)
Cook it (stirring often) until it's fragrant and dry
Add boiling liquid (water or stock)
Cover and let it cook until the liquid is absorbed
Fluff with a fork before serving.[/list=1]
It comes out really nice and fluffy, and absorbs gravy well.
And of course, if you have cooked buckwheat groats, you can make kasha varnishkes, one of the glories of Jewish cooking. (I think we had a thread that mentioned it some time ago.) The basic recipe is: mix the groats with cooked bowtie pasta and tons of fried onions (with their grease). Yummmmmm. You can add sauteed mushrooms, and if you used butter or a good oil, that makes a good vegetarian entree.
I use groats in the braising liquid for lamb osso bucco. They also do well in place of rissotto in a hearty dish.
Toast them in a dry pan, much like toasting almonds prior to cooking. The toasting brings out their color and their signature nutty flavor.