I've gotta say, for all the more mainstream pop/techno she is, her voice does make it sound interesting.
Ur so *** is a great song, and Hot n Cold will forever be in my MP3 player (due to a friend controversy and a dance involving my little sister and best friend. Don't ask.)
Though she uses the stereotypical chord progressions, she manages to phrase her words interestingly.
Not the best artist on the planet, but she does catch the ear.
(also her bass parts are catchy and fun to play)