For myself, I found it hard/nearly impossible to stand up in the saddle. It changed my center of gravity too much when really cranking out of the saddle, and I didn't feel safe. If it's got a low-enough gear, standing isn't an issue. In my case, I modified my bike to drops, and am much happier.

If I can speak a bit more on this topic. dutch-style bikes are very common where I live. I would say that you see older, odd bikes and dutch-style bikes as much as, if not more than mtbs. Although younger people seem to prefer the mountain bikes, and older people the others. One seldom sees drop bars here in town. That all said, I think the most upright bikes work best on city streets, where traffic is slow (or non-existent, such as in the no-driving zones in town), and the bike is ridden slowly. It helps when the streets are flat, as well. As soon as you get a bike out into the outer side of town, with larger roads, and faster speeds (and more room for the bike to also fly), the upright city bikes are less useful, and I seldom see them there, and if I do, they are typically on the sidewalks, and not on the road. (Our sidewalks are designed to take both pedestrians and bicycles--very wide, and crossings for bikes that are separate from pedestrians) I tried a more upright bike, as I said, but maybe my American mindset was too limited to accept the uprightness, and I switched to drops. If I had my 'druthers, I would be riding my full-blown tourer. :-)

But in any case, I can see dutch bikes being used inside the cities, but not good for many people for the commute _to_ the city.

-Jon