Things are going well for Arsenal in the league. But they might need to improve their performance a little more in the long term. This is important for especially big games. Their next game is against Tottenham in Emirates so I really wonder how this game will end.
There is always room for improvement, but to be fair to Arsenal they played pretty well against an Everton side that were only prepared to defend and hope to either get a draw or a goal against the run of play, but i second what you say, Arteta's boys need to improve more in opening teams up, especially the ones who are set to park the bus all game long.
Having said that, the North London derby next, Spurs look like a different team thus far, Ange Postecoglou is enjoying his start to life at Spurs, and they have the chance to make a big statement next week against Arsenal. The North London derby is always feisty, thus i am not expecting anything different, no prediction from me yet for that game.