It's definitely my favorite app, as well. I download the paper before I leave in the morning, so when my train into work dives into the tunnels, I can catch up on the news before I even show up at my desk! (Much more productive than spending the first 30 minutes of my day at the nytimes website.)

I prefer their WAP site (mobile.nytimes.com) to the iPhone app. The website loads faster due to the emphasis on text over images, and you can scroll past the adds. The app requires too much bandwidth and the ad placement is persistent and annoying.