Liberty City Stories is a very good addition to GTA IV. Two episodes, The Lost and Damned & The Ballad of Gay Tony on one disc.
For fun factor the Ballad of Gay Tony is the better episode, generally longer gameplay, more missions and a much better laugh. With a host of new weapons, parachutes and vehicles to play with this will keep you entertained for hours.
Players might want to turn off the noise option on Lost & Damned as it sharpens the graphics up quite a lot.
Online mode is available for both episodes, but as above BOGT is the better one, have a search around the city for the NOOSE APC tank, Stinger and the Buzzard helicopter!!
Well done Rockstar on Ballad of Gay Tony for putting fun back in GTA!!!