There was a stupid thread on the subject but last year...
Someone was going to be in his position at some point (i.e. the point at which someone actually got away with it), and it turned out to be him. Think it's fair to say that he acquitted himself pretty well, though he certainly had his bad points. A major historical figure, but no angel (and not a demon either). There were more interesting Reformers, of course.
Those wanting to knock Luther might want to note also his questionable role in the German Peasants War. Those wanting to do the opposite might consider his cultural contributions, which were considerable.