Half way through the first one. It's OK, but not terribly impressed so far. The long exposition sections begin to seem a little clumsy. I can't help thinking that there are a few rough spots in the translation. Maybe some metric conversion mistakes. And the odd untranslated word, other than making me feel like I'm walking around in Ikea, seems to be just showing off the Kindle lookup feature.
On an aside, this is the fourth or fifth book I've read on the kindle software (iPad / iPhone) but probably the most popular. There is one feature that I find annoying and somewhat bemusing. If 50 (I think) or more people have highlighted a phrase, it becomes highlighted in everybody's copy. First, I feel like someone's been scribbling in my book. Second, most of the highlighted content seems pretty un-noteworthy. Unless some spoilers are highlighting significant clues.