I was totally blown away. I went in mostly unspoiled, so I was surprised by a lot of things. It was largely based on the Infinity Wars comic of the 90s, so I have a pretty good idea of how Avengers 4 will play out. Everything will be reset somehow, most of the characters who died will be brought back. There are a couple that I'm pretty sure are dead for good.
There was humor, action, horror, and genuine heartbreak. I knew how it would end, having read the comic, but I was still stunned by it. I was like Captain America at the end: "Oh, God..."
Disappointed by the lack of Hawkeye, but apparently, he'll be a major force in Avengers 4. No Ant-Man, either, but we'll see what he's been up to in Ant-Man and The Wasp.