We can't fault Apple entirely for the live stream going down; that was probably due to too many people all logging in at the same instant all over the world.
But when the video did come back, the audio of the live stream was being covered up by a live translation that sounded like Chinese. It took Apple most of the first 25 minutes to fix that, much of the introduction of the iPhone 6.
Here's what it sounded like:
And on top of that, during the event, Apple's website went down for a few minutes.
This, too, was probably due to all the people logging in trying to see Apple's new products and watch the live stream.
By the way, Apple was turning away a lot of people from that live stream anyway. You couldn't watch it unless you were using Apple's home-grown browser, Safari, something Apple does will all its live stream events.