Actually, the last two Endless Eight episodes have convinced me that the repetitious episodes are a fantastic idea. Each one brings something new to the table, leaving us with a plethora of artistic and cinematic touches that wouldn't all fit into one episode. It's really like the Endless Eight concept in itself: they couldn't fit all they wanted to accomplish into twenty minutes, so they kept going back to the beginning to take another whack at it!
Endless Eight will definitely go down as one of the ballsiest and most avant-garde things ever attempted in anime, and I think it's working terrifically so far. It may come across as lazy initially, but it takes genuine skill to make the repetitions as visually distinct as they are. Anime isn't just story and dialogue, it's also artwork, and the variety of artwork in Endless Eight is truly special.
You know, I may actually miss it once the last three are gone...