How Bad is Galio Support?

TL;DR: Not bad at all.

I just had a remarkable experience. In a normal/draft game, the person playing adc was so upset about my choice of Galio support that he subsequently refused to lane with me. With support runes and masteries and having already purchased Relic Shield, I was left to solo bot lane while he went to duo in mid lane. We lost bot lane pretty quickly but our top laner was rocking hers. It was a bit of a slog but we ultimately WON that game.

That's just one game, though. Maybe Galio support really is bad and our adc had a good reason to be upset. Not that abandoning the lane was a nice thing to do in any case but what if he had a point? So I checked my history - which obviously isn't representative of all of LoL but which should be a good indication of my skill relative to the MMR at which I play. It turns out that I've played Galio support seven times in my last ~60 games and every one of them was a victory.

I'm going to wager a guess that isn't a fluke.