You are indeed very fortunate to have gotten your hands on a mysterious limited edition FFX with a completely different battle system to the regular version. I recommend heading down to your local game shop if you wish to gain the full FFX experience. If you live in America get an import (or the 'International' version?) for an even fuller one.

(SPOILER)It also has a slightly different storyline where Tidus actually didn't exist a millenia ago, he lived in a parallel dream world in the same time period.