For myself, I prefer to be told about the crash. But for any user who may call me as a result of the crash, I prefer the silence. A software crash may well be a one-time fluke occurrence, but many end-users are easily unsettled by an error message and will get worried, panic, etc... An app just closing itself is an annoyance, but the user knows what to do: re-launch and move on. If it persists, then ask for help.