I did not like 2 much at all and think it's the worst out of the three SOs I've played.
SO1 had a intriguing story to me and I liked the 4 main characters.
SO4, despite a lot of annoying characters and scenes, grew on me a lot. The battle system was fun. It did away with the ridiculous relationship system of the previous games. I shouldn't have to settle for a mundane ending because I missed hidden, one time events throughout the game. It wasn't a "great" game to me but I still enjoyed myself.
SO2 just never grabbed me. I didn't like the story or the characters. The whole "man behind the curtain" was really horribly done.
SO2 was the last one I played and it turned me off to the series so much I've decided there are many more games deserving of my time.