I read parts 1-3 in English. Haven't bothered with the latest volume yet though. Would you recommend reading it?
I usually make a point of finishing a series of novels once I've started it, since otherwise all the time spent on reading (and, in my case, re-reading the first volumes) seems wasted if you don't find out how it all ends. But in the case of Inheritance, I'm not keen on reading it if it turns out to be a total let-down, as some people have said...