While I have had a few arguments with friends about the issue, I find that it is largely orthogonal to my regular life. I have actually been a little disappointed by how little it has come up in conversations. Usually the only way anyone finds out is because of the bracelet and necklace I wear that bears instructions about what to do with my corpse. The friends I have argued with tend to ignore it, and if it comes up they just say something like "oh yeah, your cryo-thing". My girlfriend jokes about the "no embalming/no autopsy" bit. I have asked my family their opinions about it, not that it was going to stop me. They all said they'd support me, though my mom fought the most with me over it. Even still, she caved when I told her it meant a lot to me. Most friends don't get it, but at worst they just see it as a silly quirk of mine.

The most powerful argument I've had set against it is the ecological cost of refrigerating my ass for the next few centuries before (if!) I wake up again. After thinking about that for a long time, I decided that making babies was about as bad, since mass refrigerating is cheaper than feeding/housing/educating a new American. The if still bothers me, but not as much as investing in the stock market. Not for any rational reasons, so much as that the cost of Alcor is fixed, automatic, and when averaged over the course of a year, less than eating out every day. Though if I felt more altruistic, I'd be worried that this cost could help a decent charity a lot more than the value of resurrecting me.

But that is all tangential to your question. My answer is that nobody cares what you do with your time/money, unless you annoy them with it. Don't bug them, and they won't ostracize you. But if you can't convince anyone you love to do it too, and it works, you will be all alone when you wake up. I find that much more frightening than losing friends now because they don't like you doing weird things.