Getting Authentically Drunk Alcohol reduces inhibition, so it all comes down to what personality traits you're inhibiting, I think. I have a deep seated agreeable streak which I repress for the most part when sober, and telling people what I really think and feel makes me feel good about myself. Doesn't always help my relationships, and sometimes I go overboard and have to tone things down, but it is something of an effort. I fear strangers, and have an extremely hard time meeting new people. I like familiarity, and tend to stay quiet and get overwhelmed by new influences. I'm the type of crazy that really needs a handle on things before I like to act.
This means that I'm way more likely to become more agreeable when I'm drunk. I'll be kinder and worry about keeping people happy, and less likely to voice concerns or rock the boat. That's what I was like when I was a kid, I'd let people do just about anything without showing concern or disapproval, so when I'm drunk, I become a lot more like that.
I feel better about myself and a lot more true to myself telling people how it is, and what I feel, but I have a hard time doing it calmly, and it's draining.
I don't know about "authenticity". Maybe I'm an authentic asshole. I think that following your better judgment, which may take more thought and effort in order to do what you think to be right is better than authenticity.