Not impressed. It's something one would expect from a petulant teenager, or a Daily Kos reader. But Schwarzenegger is a 60 year-old adult man, holding an elected office which in theory at least is supposed to have some dignity. The man should have exercised some self control.
In a movie, of course, this letter would be attached to a box which contained a bomb. And the Speaker of the California Assembly would read the letter agog, mouth gaping in horror as the realization of impending death washed over her face. Tick, tick... boom! And the statehouse goes up in a Michael Bay explosion montage as Arnold does a slow-motion hero walkaway. Hasta la vista, baby.
But this is not a movie. It's real life. The Governor shouldn't be telling legislators "Fuck You" no matter how idiotic they are. It's disappointing.