According to Radiohead fansite At Ease, Jonny Greenwood isn't too happy regarding the leak. Here's what he had to say -

"So it turns out the leaked music is a stolen copy of early, unmixed edits and roughs - so we're kind of pissed off about it, to be honest. I see it like this (this is just me): there's napster-style file sharing of released music, then there's early internet distribution of what we at least consider to be a finished body of work. Then there's this - work we've not finished, being released in this sloppy way, ten weeks before the real version is even available. It doesn't even exist as a record yet.....

So yes, we're annoyed - the songs are good on the recordings, which you can hear. But we worked on them after this point until we were happy with them. This is why we're pissed off - we didn't give up on them in February (which is what you're hearing) and it's just a shame that, to your ears, we did. So of course people will still download them and hear them, I can understand the temptation. It's not you lot I'm pissed off about, it's just the situation I guess. It's stolen work, fer fuck's sake. What do you all think ? I know it'll come out for real eventually, and it'll all be fine, but I though you all might as well know what's in my head...."

Also getting into the whole album leak debate is producer Nigel Godrich. Posting on the Radiohead messageboard he said -

"Hey listen, Its not that it's not mastered........ It's not mixed! Some of it isn't even finished. comprendez?"

For a brief rundown of what all the fuss is about, read a short track by track preview here.