I always thought it was neat that with the dialog that was used in that conversation, you could kind of get an idea of what was being said even if you didn't have a great grasp of Italian. Without the subtitles it was a bit like really being in on the conversation. I had always assumed that this was an intended effect and that was why there were no subtitles.

One question about that conversation ... when Solozzo says "mi dispiace", I had always believed he was apologizing to Mike for resorting to Italian.
I recently saw it suggested that he was apologizing for what happened to Vito, following it with that it was just "business".
... which do we think?