The question is whether or not you have listened to the album in its entirety. Disc 1 and Disc 2. If someone tells me that they don't feel In Rainbows Disc One isn't complete or is lacking a biting edge, well, I'm inclined to agree with them. The best albums have a story in their subtext, but often feel wrong when you finish early or take certain parts out of context. Treefingers on Kid A is an excellent example. I'm not going to listen to it alone, but as a buffer between the chilling "How to Disappear" and the chugging "Optimistic" it is entirely essential.
In Rainbows is about context. A slow build to Videotape and euphoria, then the disintegration into Four Minute Warning. I tend to think of it as a relationship. Through the process of falling in love, you have the general sugar spiced with the occasional spike on Disc 1. At the close, the protagonist is in love and claims to be ready to face death. Everybody is ready for the end when they feel fulfilled.
Disc 2 pulls back from Videotape's immediacy and degenerates into the haunting Four Minute Warning. Alone and cold, the protagonist is faced with real death (the onset of nuclear war) and faces it with denial and fear. This may actually be precisely why I enjoy Disc 2 more. In the same way that OK Computer gives you a deep feeling of unrest, Disc 2 undoes the laces of Disc 1 and leaves you bare and exposed. Disc 1 isn't as good without Disc 2, and vice versa. It's a complete journey. That's the Radiohead I know and love.
As a complete experience, In Rainbows has been a return to the complex album experience that I missed from the days of OK Computer and Kid A. While my assessment of the actual meaning may or may not be correct, the build up and tear down over the two discs seems fairly reasonable.
And no, I don't see Coldplay pulling off anything even remotely similar.