Applause is Gaga's biggest radio hit. People underestimate how big it was. It actually peaked higher on the Hot 100 than Get Lucky did.
No one's underestimating anything. For all the exposure it got in radio play, Applause only sold a fraction of what Poker Face and Bad Romance did. That's not a good thing.
No Everyone I knew didn't really like it the first time, and no shade intended, said something along the lines of "figures" when they found out it was GaGa. The song was and is too different and not in a good way. The lyrics and lack of first listen appeal are what drew people off from it.