That's really laughable: a-ha, ha ha ha ha, ha ha ha ha. The intro is of course brilliant for a song that wants you to dance to it. It's the absolutely nonsense lyric that is utterly distinctive that you hear in a bar, catch your friends eye, and run to the dancefloor before you start trying to copy the video.
As for spending no time on her music; as far as I can see she spent the busiest year of her life both promoting an album she spent a few years making at the same time as recording eight brilliant songs to the chargrin of her record label who only wanted two for a special Christmas rerelease of the debut. And not only did she record eight extra brilliant songs, she recorded at least four songs that are so good I would personally call songs of the year.
As for the singing live bit, I'd disagree she's shit. I personally don't think that she's as great as some of her fans would have you believe, but I think if you compare her to other performers in her genre then she's clearly above average. But she's also not selling herself as a vocalist, she's a pop singer - her sitting at the piano belting out a ballad is the exception rather than the rule.
The thing is, for a few weeks after 'Just Dance' came out, I was saying everything you are. So not only did the visuals not distract me, they annoyed me. The music was so good that I managed to get through that and listen to the rest of it. The Fame was a great album, but suffered from some filler. The proof was always going to be in the second album and thankfully The Fame Monster is even better.