Hokay, I had my first genuine riding impressions today - I was out for about 55k and it was really hard for a few reasons:
1) First time out doing anything like a real ride in about 7-8 months and more than a bit out of shape.
2) The fixie factor - it is different and it is difficult, but enjoyable. You learn new things about the cadence you can hit and sustain on a long downhill, and you learn just how long you can stand up and crank on a long uphill. My normal position is that riding a bicycle isn't a leg exercise as much as it's a cardio exercise. On a fixie, it's a leg exercise!
3) The ergos on this bike are soooooo much more aggressive than the hybrid set up for touring that I was riding the last couple of years, and the road bike with straight bars for commuting that I had before that. My wrists, neck, and sit bones were f'n killing me.
So, very difficult for an out of shape guy who's new to this kind of riding, but very fun and rewarding. I love the feeling of riding this bike, it just whips around and every sensation is so immediate and direct. It's hard to describe but I'm very happy with my choice so far.