I was in Shanghai for work for about 3 weeks a few years back. For the first week, I tried to use mass transit, because everyone said it was the best way around (and in shanghai, their mass transit is absolutely world-class, the best of the best). It was absolute hell - a perfect description; I was in constant pain.

After the first week I broke down and just took cabs everywhere. Perfectly practical, but only when somebody else (in this case, my employer) is paying for it.