I love the up-tempo, rockin' feel to Reckoner. One can hear shadows of Pablo Honey if you squint your ears.
Other tracks have more of the modern Radiohead climax composition we know and love.
I think In Rainbows is a bit more diverse than any single album, with the exception of The Bends. It has a lot of elements of their sound from different periods of their history mixed together.
Having said that, to me, it seems to lose the continuity that some of their other albums achieved. OK Computer and Hail to the Thief present themselves as complete; I feel that In Rainbows is more a collection of good songs than a cohesive whole.
I've only got my download from the W.A.S.T.E. store so far, but am strongly considering picking up a discbox in the new year.