I like Mackie in the role and think the show did a good job selling that he has the heart and spirit required to take the mantle. I'm game for more.
That said, I was disappointed in 3 things that hurt Sam's ascension:
1.) The Suit. It's ass. Probably the worst I've seen in the MCU and that's really unfortunate. It really undermines his big entrance, similar to Daredevil's at the end of his first season. I know it's comic accurate but it is ugly as hell and looks cheap. It was doubly underwhelming that the suit was supposedly Wakandan made. They must have made it quickly.
2.) He doesn't get a fight, and that 'could do this all day' moment. Maybe this is just me. I wanted to see Sam take down a super soldier by himself. I wanted him to get absolutely battered, but win because he's effing Captain America. He's too often flanked by other people and I could have done with some more solo shine.
3.) The writing just isn't quite there. It's not awful, and didn't kill the show, but I'm always put off by some forced banter or weird decision. Sam's speech is less significant for feeling unmotivated in the moment, and for being aimed at generic white elites that we don't know. Likewise, as sweet as it was to see Isiah remembered with a section in the museum, it seems bizarre to omit of all the other forgotten soldiers Isiah was so passionate about.