Well, it depends on the parents, really. I feel my parents were pretty good. They worked hard to make sure one or the other of them was always there when we needed them. They were good at different things, and liked different things, and encouraged appreciation of different things. My mother taught me about Shakespeare, my father taught me about Socrates. There were some things I'd only want to talk to my mother about, and some things I'd only want to talk to my father about.
Now to be clear, it isn't all sunlight and rainbows; two people are likely to have different views on some things, and it can create certain stresses and conflicts in a kid as well. My parents were Catholic, and my mother taught (among other things) feminist literature- not exactly the best climate for a heterosexual male to learn about sexuality, shall we say. But, by and large, I never felt other than loved, and never felt that there wouldn't be someone there to help me if I needed help. And that was awesome.
I quite admire single parents who do a good job, though. It's a hard enough job for two people.