I find the subway gives me time to think, mediate and generally arrive at work stress free. On the bike you have to be alert at all times. Biking in over the last few days is hardly representative of a regular day.
The subway is actually quicker for me, especially when I factor in having to get changed twice.
Someone at work was going on about how great bike commuting is and how everyone should do it, turns out she lives 2 miles up the street. Why would you not bike that?
Maybe I'm not hardcore enough yet. My neighbor does it. He actually goes about 10 blocks further. He is a carpenter at an art museum, so can dress casual and they have showers there.
I've commuted by bike in London, Amsterdam and Toronto. If I lived the same distance away in any of those places I'd do it. Having to navigate lower Manhattan every day is more than my nerves can take at this point.