I think it depends on the guy and what kind of stimulation he likes. Sometimes my husband likes it and feels it well, but sometimes he doesnt notice. If I play with my tongue ring on his dick, then obviously he feels it and likes it. But otherwise when I am sucking him, I lay my tongue ring down in my mouth and he cant really feel it.
But at first - it got in the way LOL
I bought a tongue ring that has silicone spikes on it - pretty fun. Feels weird cuz its so big - but its an interesting feel- according to my husband.