I used to think Lady Gaga was just a hack.  She was dressing like Elton John, and being intentionally scandalous like Madonna, to compensate for her lack of talent.
Then I saw her do "Paparazzi" acoustically on a piano (ok, might have been a keyboard, but she had no production magic or AutoTune behind her).  Other than pronouncing it "Puhpuhrazzi", I was floored.  So, I know she has talent.
And she's becoming a guilty pleasure.  Her music reminds me more of Ace Of Base than Madge.  In fact, "Alejandro" reminds me of AoB's "Don't Turn Around."  And that's a good thing.  Can't stand Madonna, but I love Ace Of Base (weird, right?).
Sexy?  Hard to tell.  With her wigs and dress and elaborate makeup jobs, I can't really tell WHAT she looks like, but I think her facial structure and eyes are similar to Cher's, which is only so-so in terms of hotness for me.
But yeah, she's a force to be reckoned with, and that's cool, cuz she's not all bad.  And she's a HELL of a lot better than Ke$ha.