Franck Ribery's spotkick settled the match, but Capello insisted: "I'm actually quite happy because I have seen improvements.
"We played against a top-level team and I think we did well."
As for why he was so pleased, the Italian said: "The way we played, we didn't let the opposition play too much and especially, the way we played with personality.
"We did especially well in the first half, but unfortunately we conceded the penalty, the goal."
Asked about David James' culpability for the goal, Capello said on Sky Sports 1: "I didn't see it clearly but I don't think he could have done better."
As for his substitutions, Capello said they were not prompted by individual performances.
"No, I need to see all the players play, especially in real matches like this, to get a clear idea of what to do when the World Cup qualifying campaign starts."
As for Beckham, the Italian said: "Yes I saw him well, he was fit and could have carried on playing. I subbed him because I needed to see other players as well."
Captain for the night Rio Ferdinand admitted the result was not the ideal way to cap off his big match.
"It's disappointing but I think it's more about the team," the Manchester United defender said on Sky Sports 1.
"You could say we took a stride forward in certain areas; the players were not scared to get on the ball, we were passing it very well at times - maybe without creating many openings but I'm sure that will come.
"I'm disappointed because I'm very honoured to be captain but it would have been nice to have got a win."
Ferdinand added: "There was no prouder man on the planet today, leading my country out, but it's not about personal accolades, it's about the team and today we didn't get the result we wanted."