I think it's a pretty cool game, but it does get damned
expensive 
I have not played it myself as I don't even have a chance to get
near the machines... I saw at Bugis where they have $1 continues,
the people there have about $50 in coins and they keep feeding the
machines.
I think the game is bloody successful like this.. as for its
longevity, who knows?
Personally, I prefer a good beat-em-up
looking
forward to PS2's version of Soul Calibre II where they will feature
Heihachi Mishima from the Tekken Series