I always liked it myself. It was a way of humanizing a character that could actually be somewhat relatable. Even though "I" don't drink, I know most adults do... and Hal is exactly the kind of guy who would refuse to acknowledge his limits and do what other people tell him he can't possibly do. Whether that was reigniting a sun, escaping a black hole, or operating a vehicle while he's impaired. Besides even if they did show his beer full... I dont' think they made it clear if it was his first or his sixth...
My favorite thing about it... was that it was a one time thing after a really bad day at work. He wasn't shown as an alcoholic... he didn't screw up his friends life and then continue to drive drunk... He screwed up, then immediately (mostly immediately) took responsibility and paid the price.
As far as character assassination go.... this was REALLY mild. I don't have a problem with character origins showing them to be making terrible mistakes... as long as it isn't a core part of his character from then on. And the drunk driving was never mentioned again.
haha ... oh, Grant - you scamp!
Sidenote - am I the only one who wishes Hal had that black mask inside the book the way he does on the cover?