As of yesterday, online publications have started to post their previews on Grand Theft Auto V. This comes with a great deal more information and screenshots, which I have summarized below.

Previews:

English

• The Guardian (UK)
• IGN

Foreign Language

• Gamer (NL)
• Insider Gamer (NL)
• Meristation (ES)
• Gamersaktuell (DE) 
• Multiplayer (IT)
• JeuxActu (FR)
• Spiegel (DE)

Information:

• The game is based around hiests and robberies, similar to Three Leaf Clover, 5-6 main ones in all. Each one if bigger than any seen before in a GTA.
• Michael is an ex-gangster who is now under witness protection with FIB. He lives in a grand mansion and is well off money wise. His marriage seems to be falling apart, as seen from the interaction from his wife in one mission seen by the press. 
• There are twice the number of pedestrians in V than there was in IV.
• Franklin is a repo man working for an Armenian luxury car dealership.
• Convertibles have been properly realized in the game. Small details like this make the game seem more real and immersive .
• Dynamic events similar to the ones in Red Dead Redemption. For example, Franklin spots a Gruppe 6 van parked in a petrol station, he can either steal the van or follow for a more quiet approach. Either way, getting the cash.
• Lots more to spend your hard earn money on.
• Trevor's introduction to the press was an unforgettable one and sets up his character nicely. He is seen on the toilet battling with constipation.
• Blaine County, Alamo Sea, Mount Chiliad, Del Perro pier are some of the locations mentioned.
• Trevor is a bit of wild guy, he was seen pouring a jerry can of gasoline on a car and setting it on fire.
• The characters become closer as the missions go on.
• The game is "around five times bigger than its predecessor, and what’s visible from the chopper is about three-and-a-half times bigger than the sprawling deserts of Red Dead Redemption."
• "As ever, a mini-map in the bottom-right of the screen pinpoints your objective. It also displays an artificial horizon while flying, which pitches and yaws as the chopper circles the tight cluster of buildings that makes up central Los Santos."
• Diving is back and is much more expansive with diving equipment and underwater caves to explore.
• Switching characters is similar to the weapons wheel in RDR or Max Payne 3.
• The main storyline has a completion time of 25 hours.
• The game has multiple endings, depending on what choices you make through out.

Screenshots: