Well, the game's developed by Tri-Ace, who has made other games such as Star Ocean: Fantastic Space Odyessy, Star Ocean: The Second Story, Star Ocean: Blue Sphere, Valkyrie Profile, Radiata Stories, and Tales of Phantasia (as Wolf Team).

Star Ocean: Till the End of Time really doesn't have much to do with the previous games, as I recall, and takes place 1000 (?) years later than Star Ocean 2.

Aside from that, there isn't too much you need to know about the previous games. Though all of them are great, so you should give them a shot, too.