Stereotypes from those who likely have no experience on one. It's true, the pedals always turn, but that doesn't mean you can't stop. If you buy a complete fixed, it'll come with at least one break from the shop and most are drilled to allow the addition of a rear break. You can also use your legs to lock up the pedals and skid the rear tire. I've kept my front break on so far as a sort of 'OH SHIT' lever. Once you get over the ackwardness of the pedals constantly turning, you forget about it. I've been riding fixed for three years now, year round, even through the MN winters and wouldn't think of going back at this point.
There are definitely pluses to a fixed. They are much lighter because they don't have any shifting mechanisms. In addition to being light, there's basically zero maintenance aside from greasing/replacing the chain (the chain on a fixed will stretch faster than a freewheeled bike due to the additional pressures on the chain), and replacing tires every couple years (again, if you skid stop, you'll go through rear tires faster). I usually replace my chain once a year for the huge sum of 15 bucks or so. I also prefer riding fixed in the Minneapolis winters because I can feel exactly how much traction I've got in my rear wheel and adjust my riding style accordingly.
That said, the riding experience is completely different - in a good way. I know it sounds cheesy but you're way more in touch with the bike. If I'm flying down the road and have to make a sharp turn, I always know exactly where the pedal is going to be in relation to the ground. When coming up to a light, I need to start planning out if I can keep going or if I should start slowing down if it's yellow. If I don't think a car sees me, I can react and slow down or stop. If I'm in traffic, I feel like I'm much more in control. I don't need to jam the breaks if something comes up - I can put a touch of back pressure on the pedals to shave off a little speed if I have to.
I'd recommend at least trying one to see what you think. Give it some time and you just might like it. Like I said, I love mine. If not, to each their own - any bike is a good bike!
I have four other bikes in various configurations. One coaster, one single speed (rain bike), and a 10 speed - I'm not blind to other kinds. I just prefer fixed for the feel and simplicity.
Oh yeah, I don't wear spandex, don't have a racing jersey, and generally try to keep out of the way of cars. I'm also pretty sure you guys wouldn't call me a hipster if you ever met me in person. Pretty normal guy here. I'm not really sure how all bikers got lumped into the Armstrong crowd...