The game looks spectacular. And it will be much more interesting than Watch Dogs. Ubisoft isn't making it.

You can buy property; houses, garages and businesses can all be purchased for extra revenue sources.
You can customise yourself with haircuts, new clothes, and tattoos
Each character is rated in a series of skill categories: Stamina, Shooting, Strength, Stealth, Flying, Driving, Mechanic, Lung Capacity.
Each character has a 'Special': Franklin is an adrenalin junkie and can slow down time while driving; Trevor has a frenzy mode, where he does double damage, takes half damage, and has a unique melee attack; Michael has his own version of bullet time
Specials are governed by a meter, it drains after use and recharges slowly
Other skill categories are shared and can be improved by completing missions, side missions, activities and more
Trevor will always be the best pilot, Franklin will always be the best driver but each can improve their proficiency a little
One of the skill categories is stealth, suggesting players will be able to take different approaches to missions
Pay N Sprays can also mod cars with paint jobs, new wheels, window tints, grilles, spoilers. Upgrades to suspension, engine and brakes can also be made.
Weapons can also be customised with laser sights, scopes, silencers, and high capacity magazines
You can pick up hitchikers, do stunt jumps and flying challenges, take part in yoga, golf, tennis or bike races.
Some boats will include gear such as wetsuit, flippers and tanks for diving
An underwater ecosystem exits, "the sea is teaming with fish and sharks"
Treasures can be found underwater, but NPCs will be looking for them too
GTAV rewards exploration, there's no signposting underwater, so you'll have to find the treasure the hard way
Dives won't offer massive payoffs, but will "help grease the wheels"
The character selection wheel is split into four triangles: Franklin, Trevor, Michael, and your multiplayer character
It seems there's a closer relationship between single and multiplayer. Simply pressing Down on the d-pad will drop the play in and out of MP.
Rockstar has said it will reveal more on multiplayer in the future
There are subtle differences in the way each character moves to reflect their personalities; Michael is slower and deliberate.
Rockstar says there will be five times as many pedestrians in GTA V as there were in Grand Theft Auto IV
There's a "crazy level of detail": Tourist buses can be boarded for a tour of celebrity homes, film posters are plastered on the walls, men in comedy costumes try to corner you outside the Cathay Theatre, including the Superman-like Impotent Rage and Master Chief riff, Space Ranger.
iFruit, the game's new phone, can be used to snap pictures and upload them to Rockstar's Social Club
The phone also has apps. In addition to the camera there is internet, contacts, social media, a calendar, and a replay missions app. There are three more Rockstar hasn't yet revealed.
Michael's obsession with classic films translates into in-game set pieces based on real world movies. In the demo the three characters mount a heist very similar to the one from Heat.
'Mini heists' are used to teach the player about preparation. Players must secure vehicles, outfits, masks, the getaway vehicle.
These build up to a bigger heist where the execution must be flawless. They'll require the right crew and players will have to decide on the cheap option, which results in less skilled people, or paying more for skilled crew members that will take a larger cut.
You can switch between Franklin, Trevor and Michael during a cutscene, manually, or automatically when the AI takes control for you
Each character has a job to do, how much you switch yourself in or let the computer do, is entirely up to you
If you die the game reloads to the last checkpoint, even if two other characters are alive
Although it's up to the player when they switch, dialogue will suggest ideal moments. For example, when Michael and Franklin are being overwhelmed by snipers, Michael might ask for Trevor's help.
A combat roll has been introduced for moving between cover
There is a wider field of vision, and players can run-and-gun
A deer and a wildcat was spotted in the mountains.

Hah! Beat you to the punch! :P