I used to hate it, especially since it didn't disprove Sega's console failure trend (GG, Sat, DC premature deaths

). After a friend showed me the joys of the fighting games, I grew to love it.
Power Stone 2 - the craziest party game ever. You don't have to even like fighting games in general or know how to play. Just grab a weapon and smack up the opponent, be it an umbrella or dragonslayer sword. Trumps Super Smash in insanity. Stages have never been so persistently interactive.
Project Justice - I never thought I'd get to play this game in my life, the fabled sequel to Rival Schools. Very fun character designs, and my innate love of music automatically gravitated me towards Yurika.
Last Blade 2 - Very well ported from AC/Neogeo (?). It's a shame that this didn't grow more in popularity with all the swordplay action and repelling.
The dpad/stick made me cry, with the terribly difficult time in comparison to the PS2 controller I had with pulling of simple moves such as qcfs or even just trying to not jump.
Also, due to realizing that several great RPGs such as Grandia II and Skies of Arcadia were ported from it (or vv?), I respected it more.
Finally, DC spawned the funkiest rhythm game ever to grace my PS2 with a port: SPAAAAACE CHANNEL 5~~!
Jam it back in, in the dark.