As an American, who was NW Plat, now DL Plat, I can say that I like KLM, at least on award redemptions.
- A decent number of 747s (many American carriers don't, and DL seems to be hiding NW's 747s so I can't find them)
- The Delft houses in J
- Better TATL award availability than on DL metal
- A fantastic airport in AMS, with decent lounges
And AF has the only A380s in Skyteam -- I am flying one in a few months - rather hard to do that over here
(It will be my first time connecting in CDG -- from what I hear, I may wish it is my only time connecting there).
I'm certainly not their core market, but from where I am, it's not bad.
(I used to fly KLM TATL a lot, but I haven't recently and so I don't know whether I would get 0%, 25% or 100% in discount economy -- that would be the one major issue from over here).