I liked Sunset Overdrive. It definitely has a Jet Set Radio/Tony Hawk feel to it with crazy weapons & never-ending waves of enemies thrown in. I probably got about 6 hours of play on it and most of that was finding the collectibles hidden around the city.
The weapons were interesting, but I didn't think the combat was that good. They don't give you much ammo so you have to constantly look around for the red ammo boxes. You can't stay on the ground without getting swarmed/killed so you have to constantly be bouncing or grinding, which makes aiming a lot more difficult. Certain weapons are more effective against certain enemies and they level up depending on how much you use them. I didn't really see much benefit from the amps & weapon mods early on.
Overall, it's a decent game. The game dialogue makes fun of itself & video games in general and can be funny at times. If you like trying to figure out how to get to the tops of the tallest buildings, finding all of the collectibles, etc. then you'll enjoy it.
They only let us play it Friday & Saturday... I didn't even hear about it until mid-day Friday & the download/install took a while (plus it was my wife's birthday) so I didn't get as much play time in as i wanted.