Bruno Fernandes fired United to a 2-0 lead before Jarrod Bowen pulled a goal back for West Ham.
After Saturday's 2-1 reverse, Potter told the club's website: "It was a good workout and a good occasion, I thought.
"I thought both sets of supporters were really good. We got off to a poor start in terms of just a mistake for the goal, which can happen sometimes and then destabilise you a little bit. But I thought we grew into the game, finished the second part of the first half pretty well.
"And then, again, we didn't start the second half so well, but again, recovered and played some good football as the game went on. Jarrod scored a fantastic goal and the intention of the team was positive. I thought we just made too many bad executions, but that can happen at this stage of the season.
"So, yes, lots to be positive about, but clearly always things to improve."
On United's goals, Potter also said: "Mistakes are part of football and certainly at this stage, it's the first game for us really, certainly in this type of environment so you're going to get a little bit of that.
"But I thought the spirit of the team, the personality of the team over the course of the game was positive.
"There was a connection there with the group, so that's really good. We just have to iron those out, which is normal, and then move on to Wednesday."
Potter fielded Freddie Potts and Preston Fearon and added: "I thought the young players did really well.
"Freddie and Preston, in particular, you could see the quality they bring, what type of players they are.
"So that's exciting for us."