Everyone responds to music differently. There are no right or wrong opinions, except the ones that assert that other opinions are wrong.
All I can say is that I resonated with Kid A immediately, on the first listen. It didn't have to grow on me. I didn't have to figure out what they were doing, there was an immediate kinship with the music. My heart rate increased, I felt excited, I felt like we were from the same tribe. I have listened to Kid A regularly, and during prolonged periods somewhat obsessively, since October 2000 and I have never gotten tired of it or bored with it. I agree with Zoomerang that the production made some songs less great (Idioteque, for example, totally rocks out live) but rather than diminishing the album for me that just makes me appreciate even more how great the actual songs are when I hear different versions of them. I love the flow, I love the mood, I love where the record transports me to. I love wandering through airports with headphones on viewing the world through Kid A eyes. It's an experience for me.
But honestly...I have had a similar experience with all of their records in varying degrees. That's why they're my favorite band, because I seem to genuinely love every direction they go. I am currently having an experience with In Rainbows.