The defending champions produced a sterling comeback as they came from 40-13 down to edge out London Wasps 42-40 in a thrilling game at Twickenham.
Despite the win, Brown believes that his side has a lot to improve on and that their display was not good enough.
"We have massive standards and expectations of ourselves and those weren't met. We won in the end but we've got a lot to work on," said Brown.
"We didn't start very well and up to 60 minutes were were pretty flat, didn't get our game going and our defence was non-existent.
"We have got a massive belief in this squad, which showed in the end. We knew once we got a game going we could really push the scoreline. All credit to Wasps. They were awesome. If they play like that for the rest of the season, they'll definitely be pushing hard for the top spots."
Quins face London Welsh at The Stoop in the Premiership on Friday.