I have always considered Monty to be an excellent "defensive" general but believed he lacked something in attack mode eg Operation Market Garden.
What do others think?
There is no such thing as a "Super General" they all are humans and make mistakes. I would rate him in the group of the better Generals of that time. Marked-Garden failed due to different reasons. Not taking the Reports of the dutch Resistance serious, the quality of the pictures made by reconnaicance planes was just bad, underestimating the difficulties of the dutch landscape and overestimating the own abilities (one bridge to far), Beside all these points, there is, atleast in modern times, no military operation planne by ONE man only. Of course, in the end, always ONE is choosen to be responsible and take the blame in case of a failure and to share the glory in case of a success.There have been mistakes we can say, now, after it hapened, could have been avoided. But, they didnt have high resolution spy sattelites, the reports from the dutch resistance have been bogus a few times before AND there was a race going on between the western allies and the russians.
If some officer was suggested to join the Prussian Army, or to be promoted, Federick the Great used to ask: Does he have Luck. Luck, beside good planning, well trained soldiers and good hardware is the most important for a commander.
I personally think Montgomery, and others, should be judged by their overall archivement, not by a single failed operation.
So, I come back to the start of my post, I think he was surely one of the better generals in WWII.