I would say yes.
Big cities make me nervous. I used to always end up in the wrong lane and get forced to exit. People also like driving 20mph over the limit which makes it more nerve-wracking for someone not used to the area. Where I come from, the biggest divided highways only have 2-lanes each direction. Several years ago, I was driving through Kansas City, MO, got confused, lost, and ended up on Prospect Ave at 2AM. There were people still wandering around at that hour... not real wholesome looking people at that. Prospect Ave isn't the best place to be, it's been on the A&E show "First 48" when they followed the investigation of serial killings of prostitutes. Dead hookers were showing up all over Prospect Ave and nearby areas. Every stoplight, the wife and I would say, "TURN GREEN, oh PLEASE TURN GREEN!" Back then, we were only armed with maps and directions printed out from mapsonus.com.
More recently, armed with my D2 (and the Z1 is better), I was able to get through KC with no problems. It told me which lane to be in very early, let me know ahead of time where all the turns would be. It was smooth sailing, and it allowed me to focus on driving. I was able to drive more comfortably with confidence and had no trouble keeping up with traffic. There were no wrong turns, no scary neighborhoods, no fear of missing a turn or exit.
I had no problems in Winnipeg, MB either. That's an even bigger city of 685,000. I was able to get around, no problems. The only frustration was the roads under construction.
Personally, I will not travel to a large city without navi ever again. It makes all the difference in the world.