Now that the season has hit the mid-point, it seems logical for the writers to make some sort of statement regarding Johnny and Sarah. With the two of them in close proximity, given their history, the emotions are clearly running high. Up to this point, they've been keeping those emotions in check, largely due to the circumstances of Walt's death and the complexity of the family situation. It's not so much that they don't want to be together, but that they've had several reasons to keep it from happening and attempting to move on beyond their shared past.
The previous episode was designed to remind Johnny of how important and central Sarah is to his world. This episode compliments that by forcing Sarah to consider their history and how much they still mean to each other. The induced coma, while part of the larger mystery, was the device for pushing 12 years of psychological angst to the forefront. Sarah had to contemplate life without Johnny again, and it cut her to the core, breaking down the barriers that circumstance had placed in their way.
If both of them had come to the separate realizations without something to bridge the gap of uncertainty, the momentum for a logical return to romance wouldn't be there. Instead, the writers manage to use a fairly simple situation as a hook into a mystery that gives Nicole de Boer a chance to tackle some unfamiliar material and Johnny a chance to see things from Sarah's perspective.
The mystery itself was not particularly compelling. It was easy enough to guess what was happening, and the eventual details did little to give the concept more weight. Instead, it was the clever use of the vision and the interaction between the characters. It was great to see Sarah take action, breaking out of the mold created for her character in previous seasons, and as already mentioned, the structure of the episode made the ending a logical and sensible consequence of the ordeal.
All that said, it is also clearly the mid-point of a larger arc for the two characters, and as much as the relationship might be turning towards the inevitable, this feels less like a resolution and more like the calm before the storm. The happiness of this particular moment will likely be shattered, especially since Walt's legacy is still lingering in the background. It's that sense of uneasiness that makes this an interesting development. This is simply not going to last, and the sense of stability now will give Johnny something to fight for on a personal level as things get darker.
With much of the story construction in place and the cast hitting the right notes for the characters, much of the episode's lackluster tone falls on the direction and editing. The final act especially is rushed and Johnny's immediate recovery from an induced coma and surgery is hard to reconcile. Some of the editing issues were more reminiscent of the previous two seasons than the new status quo would have suggested.