I have gladly followed this line of games since the prequel game that came out just as
Episode III premiered (granted, that wasn't really all that long ago). Where the first game covered the prequels and the second one let you play through the original trilogy,
Lego Star Wars has had a couple of face-lifts and chances to clean up some of the issues it has had over the years. Well,
Lego Star Wars: The Complete Saga does a great job of not only combining both games, but also taking the best practices from them as well.
This game is a pretty basic action-platformer. You will work your way through each of the six episodes (each episode is divided into six chapters) in order to collect studs to be used as money, mini-kits to build ships and gold and red bricks in order to unlock new extras or areas in the game. For people who mostly played the more recent game, Lego Star Wars II: The Original Trilogy, you probably won't notice a great difference in the Episode IV, V and VI sections of the game, since most of those are direct port. Where most of the changes take place is in the first game's transition since it not only implements features like vehicles in normal levels, but also more free-flowing styled vehicle levels.
Having played the original game quite often, I found it pretty obvious what kind of changes were made. Besides the added free-roaming vehicle level where you chase down Zam Wesell, the "Gunship Calvary" level has been redesigned and all of the vehicle levels now have a Free Play mode that lets you cycle through your unlocked ships as seen in the second game. Other alterations to the prequels involve a lot of areas that were previously accessable (typically via an Astromech) and can now only be gotten into with a bounty hunter or stormtrooper, something that threw off my highly efficient run-through at first.
One of the changes that were made for the second game, but removed for this one, was the need to achieve True Jedi (collecting a certain number of studs in a level) for both Story and Free Play modes. Instead, the game reverts back to the prequel version where completing this task in either mode is all you need to do - which is good because a lot of times it is easier to get studs in Free Play mode since you have a wider variety of characters with specific abilities that you wouldn't otherwise have in Story Mode (i.e. bounty hunters, double-jumpers, etc). There is also the added bonus of more characters to either play as (like Zam Wesell or Watto) or just see walking around the Cantina (a remodeled version from the second game that acts as a hub for all of the levels).
All that being said, the core gameplay itself hasn't really changed all that much since the original Lego Star Wars game. You will still switch between on-screen playable characters or let your buddy pop in/out as needed. Jedi can still use force powers to build or movie pieces while shooters can use grappling hooks and bounty hunters can throw bombs (okay, that last one was added in the second game, but you get the idea). As it is, the gameplay is still the same quirky fun experience it has been since the start.
As an added bonus, not only does the game let you see a preview movie of the upcoming Lego Indiana Jones game, but you will also be able to unlock and play as Indie in this game.