Why do people want GGPO in games so badly

Fight game fan are constantly praising GGPO and talking about how flawlessly it performs. But no real test has ever been done, the only retail game to ever use it wasn't even a fighting game.(Final Fight: Double Impact) So why are people so sure it would perform the same under the stress of a real retail fighting game release. I guess we will find out because Skull girls has just announced that they will be using GGPO and people are acting like this will be what makes the game, One commenter when as far to say "this is a day one buy for me now" .  
 
I just don't get it why do people love GGPO so much, why such faith in this product?

what the eff is ggpo

" what the eff is ggpo "

This paragraph scares me. 
 

How does it perform?

Thousands of gamers are already using GGPO to play classic, old school fighting games against opponents around the world. GGPO's latency hiding techniques maintain the illusion of lag-free gameplay even during intercontinental play.

Play a game on GGPO then play SSFIV on xbl and you'll understand the difference.

" This paragraph scares me. 
 

How does it perform?

Thousands of gamers are already using GGPO to play classic, old school fighting games against opponents around the world. GGPO's latency hiding techniques maintain the illusion of lag-free gameplay even during intercontinental play.

"