I have been listening to her for almost a year before she became famous. I never thought she would become famous because her music was just ok, nothing that blew me out of my shoes nor anything that I couldn't stand. It was just good music and I never understood why she is so popular so suddenly. There have been others who have had lyrics, hihop, and electronica mixed in one, they just didn't market as much.
That said, I love hard rock, and rock. Then Alternative came along and I love that too, and electronica has always been a favorite and I like the newer ones. That said, Lady Gaga has yet to even match Madonna's level of relevance, from back in the day, much less "most relevant ever."
Basically, she isn't great, but neither is she bad. She's just ok and that's plenty enough reason for me to put on her songs now and then.