In his first ten years Wenger revolutionised not only Arsenal but English football. His transfers were usually spot on (Petit, Vieira, Overmars, Pires, Ljungberg, Henry, Fabregas, etc) and they were a joy to watch. The titanic battles with SAF's Man Utd were brilliant. Vieira v Keane - you don't see passion like that in today's insipid game.
However it is a shame a lot of people will remember the last few years - his spineless teams and poor judgement on players. I'm not sure what happened. Arsenal were never bad but never really very good again. They've not been same since they left Highbury. They lost something when they moved to the Emirates, and so did Wenger.
I'm old enough to recall his early days and that is how i'll remember Wenger: A visionary of the era.