Intuitively, I think I'd make a lot of people happier, but it might depend. If others were around, it might make them jealous. Or if it were the "wrong" sorts of things (attractiveness, how great their breath smelled, or anything else that makes someone a little uncomfortable), it might have the reverse effect.

If you mean it simply and basically as in telling people I really appreciated their suggestion to a problem, their work ethic, skills I admire, their level of compassion, etc... then I think it would make many people happier and feel more valuable.

They might reciprocate, as well. Double win.