You need to be careful of the carbohydrate content of alcohol, which can sometimes be high.
In large enough quantities, alcohol also reduces your blood sugar (which can be a problem if you are prone to hypos).
I don't drink much, but I sometimes have a few glasses of wine when I'm on a business trip and have less control over my carbohyrate intake. It usually works quite well, I rush back to my hotel expecting high numbers and end up getting low. (I scoffed 3 cupcakes and a steak sandwich at my wedding, and still ended up with my BG in the 5s.)
To be honest, I'd probably drink a bit more, if I wasn't trying to lose some weight.
Like everything else, you need to make your own decisions about what's good for you and what's not. I think most people think that drinking in moderation is not overly harmful and may even be beneficial.