Arteta has done an excellent job since taking charge of Arsenal, he has managed to make Arsenal look better than before. Arsenal's squad is also very good, even though their average age is still young, they are able to make Arsenal always a regular team that appears in the Champions League. Arsenal's current weakness is not due to the coach's inability to handle the team, but because they do not yet have a winning mentality.
Some last seasons of Arsene Wenger, Arsenal fell a lot in quality and competitiveness and it lasted many years after that. It only started to change and improve since Arteta return to Arsenal as their head coach. If we recall, the appointment of Arteta on this head coach position caused a lot of worry but up till now, it's a good decision.
However Arsenal now are going to a new challenging period with which they need to win titles, not only to be an impressive runner-up in Premier League or only go a little bit far like quarter final in Champions League. Arteta must help Arsenal to win titles in next one to like three or four seasons. If he fails, his position will be insecure and maybe taken over by someone else.