Need to catch up on the story before you get MGS4...here's your chance.
MGS2 seems to be the same as the Substance release with access to the "Director's cut" of the game. It includes the more than 200 VR missions scattered through four different game play modes, as well as alternate missions. Also players can check out the Snake Tales, which are five additional stories explore, as well as unlockable characters and Skateboarding.
MGS3 seems to be a little of a disappointment because it doesn't include the bonus disc on Subsistence. That means that items such as the multi-player mode, Duel Mode, Demo Theater, and original Metal Gear games have been excluded from this collection. Some might not mind because you couldn't play online anymore even if you had the disc, but the original Metal Gear games were awesome. They did however keep the improved 3rd person camera.
All in all you can't beat this collection for this price. If you're missing any games in the collection I'd recommend picking it up...and definitely get it if you don't own any.