We to a Lugnuts baseball game Thursday night, and naturally had to test out the Pre (& the 3GS). First trial was at about 6:30 pm to fire up the AccuWeather apps and check for "game time" temperature and a look at the radar, since showers were threatened.
The Pre popped up in about 5 seconds. The 3GS spun it's wheels and stalled out. Even though both were showing 5 bars and 3G status, the AT&T network was apparently overloaded in downtown Lansing just after work hours.
A later trial between innings (around 8:30 pm) found the 3GS back to life and responding in 5 or 6 seconds, too. 3G speed is great -- but only if you have it when you need it.