While everyone was complaining about Vista, I was merrily using XP. I used to listen to people saying "UAC is so super annoying!" and wonder what great evil Microsoft had brought upon the world.
Then I upgraded to 7 and saw what UAC was. My reaction was: "This? This is what people were complaining about? Seriously?"
Now I'm not sure how effective UAC is securing anything; I know most people click it away without reading it. Even if MS made a pop up saying "Running this will wreck your ****" most people would click continue anyhow...
But as an annoyance it doesn't even register on my scales.