I think everyone is being critical on the fact that they shouldn't be spending time in the AU with only 5 epsiodes left. But at the time of filming, they didn't know that they would be canceled. (okay, so they had a really really good idea they would, but we'll forget it) And besides, I watch Trek to learn about the universe, the species that inhabit it, and follow the events that take place in it. The continuity and ripples that spread through this universe are what make Star Trek what it is. No other television show can say they do what Star Trek does.
That is why I think it's great to see an AU episode from Enterprise's time. Sure it would have been better if the real crew would have been involved. But then everyone would be complaining about continueity! "ARARARAR They didn't know about the AU until TOS!!!!" You can't win either way. And, I don't get how they traveled in time, either. None of the other universes did that. But, with two part episodes, you always have to leave judgement until you've seen the whole thing. We've learned that in the past.
But for now, i'm going to go watch that episode again.
