Exact same here. Loved him, went to see his show when we were in New York. Can't stand the jerk now because he is so one sided.
I used to watch him regularly when I was younger and stayed up late. I found him to be be funny in a quirky way, sort of like how Steve Allen was. He was brought in as the young, hip guy that was an alternative to Johnny Carson and his ilk. Now, Letterman is is just a bitter has-been. He can't tell a joke because he is no longer funny. He's become a bitter partisan hack. If you met him somewhere you'd avoid him because his bitterness is so obvious you'd find him repellant. Bitter old farts are not funny. The fact that he refuses to make a joke at Obama's expense shows that he just doesn't get "funny" anymore. He's no longer about humor. R.I.P., Letterman.