Obviously I never saw him play. But I know the stories about WHY he was regarded as special. He could do things that left his peers in awe. In the days of uncovered pitches, a sticky wicket could see your whole side bundled out for <100 easily. Teams even resorted to reversing the batting order at times just to hope it dried out by the time the batters got in.
Trumper came in at 2 down, on just such a wicket with both openers out. He proceeded to strike the ball beautifully and scored a century before lunch on the first day of the match (never done before, not sure if it has since), as if batting on a paradise, while everyone else played on a dog.
He wasn't interested in easy runs, just the challenges & would give his wicket away trying to entertain the crowd if he felt runs were easy enough for someone else to score & played often on uncovered pitches, so by modern standards his averages aren't remarkable- but they ARE very good when compared to his contemporaries in the same conditions. He played attacking cricket, daring cricket and was by every account, stylish to watch.
Bradman is the remorseless run machine in our cricketing history, pitiless but not always pretty like the S Waughs, McGraths and Borders. But isn't exactly a stylist. Trumper was a romantic ideal of the other side of Oz cricket- the Keith Millers, the Adam Gilchrists, the Richie Benauds.