Oh God, a pedantic lecture about what I'm supposed to think.From a production standpoint, yes. Clip shows are episodes that repurpose pre-existing footage in order to save the production time and money. If the recycled content happens to be new to the audience, that's a nice bonus, but it's irrelevant to the functional and logistical reasons why clip shows are made. "The Menagerie" was a way to compensate for falling behind schedule by making two episodes' worth of content in a single-episode production slot. And it's not the only time a show used its unreleased pilot footage to make a clip/flashback episode. Gilligan's Island did that with their first-season Christmas episode "Birds Gotta Fly, Fish Gotta Talk." There was even a Xena: Warrior Princess episode that used a failed spinoff pilot as an extended historical flashback.
Son, I watched this episode on its first airing. I was thrilled to watch it. Seeing the "old Enterprise" and its original crew, a young Spock, the original story intermixed with the new one... it was all brilliant to me. Back then we didn't know anything about "unaired pilots;" unless there was an article in TV Guide, we just took the episode as it was presented.
"Compensating for falling behind schedule" is nothing but a trivial look at production history. It doesn't take away from the story they told because it is just trivia.
It was a well told story that stands on its own merits. How many dollars were saved is irrelevant. That they made it a two-parter should be a hint to you that they felt at the time it had meat.