What else can you say about a game that is so compelling with it's story, controls, and environment. Grand Theft Auto IV brings everything you loved about the past GTA games and also brings something new to the series.
The new addition of the cell phone is amazing because now everyone is dependant on a cell phone and this is clearly shown in the game as you start missions, call dates, detonate a bomb, take pictures, start multiplayers. etc... all through your phone.
GTAIV has also added the new cover system which works sort of the same as Gears of War, but not exactly. Overall GTAIV isn't a game which can be described in so many words, but must be played to experience this fantastic new development in the GTA series.