The snobbery about Rafa is very telling. A manager does not have to be on an upward curve in his career before being appointed. A bad spell here or there is not a definitive indication of a manager's ability to be successful at a club like Arsenal.
How his methods would work in the stable environment Arsenal offers, free from politics at board and dressing room level, should the main consideration on your mind. The things I want from Rafa is his style of football, tactical nous, strong personality, discipline and top level experience. I'm not saying he should be first choice but he should be considered, we could do lot worse.
Rafa has done exceedingly well at Newcastle. The fact that they're top of the championship is nothing to turn your nose up at, Championship is one of the most difficult/competitive leagues in Europe and returning to the PL first time of asking is not an easy task when your dealing with all the issue related to PL relegation. The mentality and composition of the team has to be absolutely right.