There's certainly room for improvement, no doubt about it. I would absolutely love to see these missions have a limited life scenario, where you could gain lives by staying alive up to certain checkpoint. I'd also love to see scoring implemented and the difficulty scaled to the amount of players in the mission.
However, I'm not sure what you and Over are expecting; almost every Halo mission ever has been a linear progression that ends in a button push of some sort before moving on to the next linear progression and button push, etc. I certainly didn't expect to be wowed by some spectacularly involved story that perfectly combined the campaign and ODST's Firefight, but to a lesser extent, that's what we're getting. The trouble is, it's combining Reach's Firefight with a campaign, which at the moment isn't as fun as I'd hope it would be with 3 other people.
I want this mode to succeed, because I can see the potential and I'm on board with it. Solo Legendary is almost more fun than the campaign so far, but again that isn't supposed to be SpOp's intent. I hope that the more regular updates that are going to affect matchmaking can be mirrored with Spartan Ops beyond just adding new episodes.