'JJ',
'Windom' antennas work well if they are used/erected
properly. They aren't really any 'better' than any other
antenna used properly. The 'all band with no tuning' is
more 'sales hype' than fact. But, they do work.
I think the particular antenna you are looking at is
more accurately called an 'Off Center fed' than a 'Windom',
but that's sort of 'picky'...
'Doc

PS - I also think the price is sort of 'steep', for a basically
simple antenna.