I wanted to know! So this morning I thinned out the radish patch and pulled out a few small "Purple Plum" radishes that I deemed hopeless, plus one rogue white radish that was just big enough to add to today's salad.
The radishes have been slower to mature than I'd like, probably because a few of them are too close together and because the soil is a bit too rich for a good radish crop. We're looking at a 40-45 days to a radish harvest, as compared to the 25-35 days claimed by the seed packet.
I was really curious about how the radish greens would taste because I hadn't been able to find a definitive "answer" online. Some people seemed to hate them and others to love them, but no one described the flavor. They're just not eaten often enough for a lot of people to have opinions about them.
To me, they taste pretty much like any other sauteed green, though I'd never eat them raw. The flavor is perfectly fine. Not exciting, but not bitter, or tough. Fine, just fine. Radish greens are no culinary wonder (unlike ramps!), but we'll definitely have them with dinner a lot this month.
Now that I've satisfied my curiosity on this issue, I'm back to waiting for this slow crop to mature. Whether or not the other radishes "bulb up", at least their greens can be put to good use.