The on-loan Real Madrid midfielder has attracted criticism from some former Arsenal legends for his lack of impact to date.
Martin Keown, the former Gunners centre-back, said he shouldn’t be in the team ahead of academy graduate Emile Smith Rowe.
Keown’s former team-mate Nigel Winterburn, meanwhile, suggested he had ‘not done enough’ during the first few months of his loan spell.
Arsenal manager Arteta sees the picture rather differently and has been impressed by how the 22-year-old has conducted himself since arriving at the Emirates in January.
And he hailed his attitude and workrate as ‘phenomenal’ as Arsenal consider whether they will extend his stay beyond this season.
‘I’m really happy with him,’ said Arteta ahead of Thursday’s Europa League clash with Olimpiacos.
‘I think he has settled really, really quickly within the team, with what we demand of the players.
‘His behaviour, his attitude, his workrate has been phenomenal.
‘But overall I am really happy with him.’