Xevious was one of the first (but not the first) vertically scrolling shooters, and was released in 1982.
Pro First TV ad in North America
It wasn't the very first vertically scrolling shooter, but to differentiate itself it was the first game that was featured in a TV ad in North America. This really helped increase its public interest, and was revolutionary at the time setting precedent for the game ads we see on TV today
Pro Very detailed landscapes for the time
As your ship is flying over the landscape, the landscapes can eventually change from one scene to another. Some of the landscapes are heavily forested areas, and others are airbase themed. This helps give each of the 16 areas a different and unique feel.