The Royals were comfortable 2-0 winners over Crystal Palace on Saturday thanks to two quick-fire goals from ex-Fulham striker Pavel Pogrebnyak and Adam Le Fondre.
The score remained goalless at the break but the Royals stepped up a gear in the second half and produced an assured performance against Dougie Freedman's men.
McDermott said: "We've got to where we needed to be as far as performance is concerned, especially after the break when we raised it, got good service to the wide players and they delivered, so too the strikers and midfielders. We kept a clean sheet too, so we're ready to go."
He added: "The first half was a little bit low tempo for us, we have to be on the move, high tempo and passing it. We did that second half, got in behind them, scored a couple of goals so we're happy with that to finish off pre-season."
McDermott gave starts to a number of the new signings, including Chris Gunter, Garath McCleary, man-of-the-match Danny Guthrie and Russian striker Pogrebynak, with the latter clearly impressing the manager with his first goal at the Mad Stad.
"It's important to get your first goal," said McDermott. "He was unlucky first half, made a great run and Danny Guthrie played him in but he was unfortunate just to knock it over. We'll save them for the league though.
"Both strikers worked really hard, and we got Noel [Hunt] and [Simon] Church some game time as well, it's important to get people on the pitch."
Speaking about the new faces at the club, he said: "I've been delighted with all the new signings since we've brought them to the club.
"They're all good guys who work hard and want to get better. They've got undoubted quality, and add that to their desire you've got a good recipe.
"We're just trying to gel the group, we've got two players for each position which is what I wanted of course."
All focus will now turn to the start of the Barclays Premier League when the Royals host Stoke City at the Madejski Stadium on Saturday (3pm ko).
"We'll prepare right, it's an international break of course as well," he said.
"We'll look at Stoke, I know Tony Pulis quite well, he's done a phenomenal job and we know it'll be a good game.
"We're at home, it'll be a full house, and we're back in the Barclays Premier League, just a fantastic place to be."