Banned in China: The Thai government called for the ban of the game after a Royal Thai Police officer caught an 18-year old student who killed a cab driver. He admitted that he wanted to rob him to get some money to play in the arcade, especially since the suspect said he wanted to see if it's easy to rob someone like in GTA4. As of 2013, the GTA series are not allowed to be sold in the country for commercial purposes.
Dueling Games: This game came out around the same time as Saints Row 2, and each of these two games have almost diametrically opposed design philosophies, which means a lot of gamers tend to favor one over the other.
Early in development, Rockstar considered setting the game not just in New York City, but in New YorkState as well, a la San Andreas, complete with their own renditions of the Hamptons and the Adirondacks. While this was dropped so that they could focus on Liberty City and Alderney, references to an area called "the Carraways" (presumably based on the Hamptons) do come up in the dialogue. Grand Theft Auto V would later include a countryside region based on rural and coastal areas of southern California.
The mission "Pest Control" was originally supposed to let the player choose between killing Ray or Phil. This was cut because it would affect the Deal Ending, where Phil assists you during the mission.
Some vehicles from previous games were going to appear, with several even completely finished within the source code.