I have flown on KLM 12 times,as well as BA, LH, AF, SR, AL, and other european airlines. I have always had very good experiences in every class of service. The 743 is a nice not very old plane. There honestly is no more turbulence on it that a 744, it has nothing to do with what kind of plane it is. As far as the staff go, the Dutch people are as friendly as they come. Always smiling and happy to give you a extra bottle of wine or an extra cheese crossaint for part of your breakfast.
Seats are very comfortable but the recline is a tad sharp as with every airline. But World Business class is sumpreme.
YOu will always find current movies, always at least two, and some sort of entertaining TV show while you eat. The hospitality is much better than BA, LH, or AF. Amertdam Schipol is honestly one of the best airports in the world, according to me and Travel and Leisure. Very easy to get around, everyone speaks english. YOu won't be disapointed by your choice.