This expansion for GTA IV sets a high bar for every other expansion to meet. A must play if you own GTA IV or not.
While the first expansion, The Lost and Damned, was dark and gritty and had no real fun or absurd missions, TBOGT goes all out. You'll find yourself driving every manner of vehicle including attack helicopters and tanks. Plus you'll find yourself parachuting off of choppers, buildings and even a plane. Add some great new weapons, and you've got a well-rounded package. Many of the missions are fun and interesting, with absurd and laugh-out-loud situations. And the story of Luiz and Tony is interesting and mostly coherent.
Throughout the main story, you'll find yourself running into Niko and Johnny a few times. The story itself ties directly into the diamond heist plotline that is so important in both the main plot and with the Lost and Damned. There are also plenty of other things to do, such as cage fighting, drug wars, and base jumping amongst other activities. Overall, for the cost of this expansion as DLC, or as part of the Episodes from Liberty City retail package, you get more than your money's worth! TBOGT alone has more content than some full games.
While TLAD's achievements were relatively simple to obtain, TBOGT added a scoring mechanic to the missions which make a bulk of the gamerscore difficult to get without having to replay them multiple times. This forced difficulty, and some hard-to-control helicopter and parachuting missions are the only real low points for the expansion. That, and perhaps some boring repetition on the drug wars. Beyond that, The Ballad of Gay Tony is well worth playing, either as DLC to the original GTA IV, or as a stand-alone game purchased in the Episodes package.