It seems to me that life is fairly easy, and probably relatively common throughout the universe. But when I say life, I'm talking about single cell microbes.
The chances of those microbes existing on a suitable planet, and then evolving into higher life forms is pretty unlikely though. Also remember that as life grows in complexity, it becomes more and more fragile. For life to exist undisturbed (no asteroids, super volcanoes, etc.) for a long enough period of time to evolve into something intelligent is something less than probable.
Now take into account that these intelligent beings must build a civilization, progress technologically to about the point humans reached in the early 1900's, and then somehow avoid blowing themselves up as they wait centuries for someone to hear their radio chatter.
I'd say we humans just won the intergalactic lottery, and we're probably the only ones.