On substance, Biden and Ryan played each other more or less to a draw; perhaps a slight edge to Ryan. I agree more with Ryan personally, but Biden did not appear to be lacking for facts and figures for people more liberal to latch onto.
On style, Ryan won handedly. Biden's bizarre smirk, the constant interruptions, the weird sounds, his disrespectful mannerisms...; I was impressed how 'cool' Ryan managed to keep.
On the moderator, this appeared biased against Ryan. Not the entire debate, but when the moderator intervened it was almost always against Ryan and in favor of Biden.