It's great for keeping an eye out of what versions are being used so you stay up-to date with all your plugins/themes! So far it hasn't been as useful in terms of preventing updates from breaking things; however I'm sure there will be more features added soon that would make this process much easier (or perhaps have some sort of notification when certain themes or plug ins need updating). We've seen many instances where our clients' websites were updated by someone else without them knowing about it which can cause problems if they're not aware until after everything has gone live - we use lookouts to keep tabs on these situations before users even know anything went wrong.