I'm surprised at how good this game really is. It's ALMOST like GTA, just cut short by the ultimate "fun-factor", as with the demo. Blowing things up is so amusing...
I'm 25% through the game so far, and is now starting to become more challenging. Though, it makes it quite easy to complete a mission knowing you can revive your partner(s) when they die. I suppose that just adds to the fun!
The activites must be the best part of the game so far. The most fun one must be the Mayhem Activity, where you have to cause as much damage as possible to property. Things blow up easily with your unlimited ammo, so it can be quite easy to complete. Blowing up trailers on a truck near parked cars makes parts fly everywhere, using a petrol bomb to catch people on fire, taking people out from a distance make it all very fun! The insurance fraud Activity is great, too. I managed to complete all of it, with my highest one being around $165,000 for diving into a path of an incoming car coming off the highway at high-speed.
The graphics are awesome. Most things are sharp, clear and easy to see. Explosions are awesome, buildings, cars and the road have the right lighting and shadows that the GTA series seriously lacked because of the PS2's and Xbox's limitatons. The characters don't look too bad either. Just a shame there is a lack of blood...
The physics can be quite hilarious. Run someone over at high-speed and they fly right into the air. Hit cars with a truck and they blow up.

Most things are quite realistic, but the cars are still quite arcady (probably done on purpose) and there are a few glitches, like cars not moving at all for no apparent reason or not being able to get out of a car at all, having to load your last save.
Overall, I would rate this game highly, probably 8.5/10 for what I've done so far. Hopefully it gets better. 👍