Depends which series you're flying on, at least in my experience. I flew on a 747 for the first time in March of '00. It was a NW -400, out of DTW, and it was great. It felt really powerful on takeoff and climbout, and was very comfortable to fly in. Conversely, my second flight was from PEK to NRT on the first leg of the return trip. This was a NW -200, and was one of the most rickety-sounding planes I have ever flown on. The interior made me feel very 1970's, and the aircraft made several loud and disconcerting noises on both takeoff and landing, and generally had that falling apart feeling to it. I was quite happy to see that a -400 was going to be taking us from NRT back to DTW.