Timesplitters was a good game, I never completed single player, but played a decent amount of it and played a good amount of multiplayer, but really the series ended with the first one. A large part of it's popularity most likely has to do with that there were really no other shooter options for the PS 2 when it was first released. The Red Faction series was the first major blow to it, and there are countless other options that are more then likely better then it (especially if you count TPS). If you also count motion controls, you also have at least Golden Eye Wii, which I would go back and play some more before touching any other games from that series.
wait what is this post
the first Timesplitters isn't that great. It's not awful, but not spectacular. 2 and 3 are the best console FPS games of that gen, and maybe ever.
--
http://www.youtube.com/watch?v=npHDxSvwCE0