It's pretty cold here in early summer -- I was wearing a sweater and a winter coat a few evenings last month. I just spent seven years in Seattle (aka the Gloomiest Place on Earth), and even I think it's a bit ridiculous to be wearing a winter coat in July. I also routinely run into tourists over by Giants Park who underestimated the weather, and who are frantically searching for warmer clothes.
That said, I like it here. But had I moved here from LA or anywhere with heat, I would have probably been sorely disappointed.
I'm enjoying my first SF (well, Emeryville actually) summer after three years in Sacramento, where "summer" means "90 straight 100+ days". I think it's nice that even on the hottest day of the year I can still walk around outside for an hour without feeling like I'm going to die of heatstroke.
Unless you're planning a day at the beach, I think "hot" is overrated (and I say that as a Sydney native).
Emeryville is a significantly different Micro Climate than San Francisco. There are even parts of the actual _city_ of San Francisco that have different weather patterns - and just go a little South down the peninsula, and it's like you are in a different State when it comes to the weather.
That said, I like it here. But had I moved here from LA or anywhere with heat, I would have probably been sorely disappointed.