I'm very impressed by Nvivo transcription so far. You probably know this already, but the biggest frustration for me currently is that the algorithm has a very hard time telling where sentences end. In some cases missing a period completely changes the meaning. It seems like it's primarily using the length of a pause to determine end of sentence. This results in lots of extra periods, which aren't a huge problem. However, my interviewees, who are speaking casually with lots of disfluency, frequently have very short pauses between sentences, resulting in Nvivo leaving out the period. Missing punctuation, I find, sometimes changes/obscures the meaning.