After sleeping on it overnight, I finally decided to go with 'Very Good' for a variety of reasons: Noble's wonderful performance as the ever-changing Walter, Henry Ian Cusick's guest turn, the humor, and the surprise at finding out that Belly wasn't dead, but had been part of the group that got encased in amber three years from now.
That said, I have to agree with startrekwatcher
that taken overall, the ep was a bit disappointing in that it didn't resolve itself, or show us how it fits into the DRJ plot. While I'm assuming that it will connect by the finale, it does seem a little late in the game to introduce this type of Lost-style of time-hopping. As I posted somewhere above, I seriously believe this to be the single dangling plot-thread that Lance Reddick said could be used to take the show in a different direction for a theoretical Season 5.
The big question for me is Bell - I clearly remember Walter stating earlier in this season (altered timeline) that Belly was NOT alive, though no explanation was given for his demise. Clearly, it couldn't be the same as in the original timeline, as his death there was connected to rescuing Peter. Of all the unanswered questions, this is the one I really want to see addressed.
All in all, I was entertained and enjoyed it. There's still a hell of a lot to resolve in the three episodes that remain and I will be sorry if that's all we get.