I played the hell out of the GTA games (3, VC & SA). Loved them. But there is something here that feels a lot better on the mechanics. On the GTAs, I always felt like a fish out of water when on foot. It just wasn't very satisfying. On Crackdown, it's unreal. I always feel like I'm in full control. I can run, leap, move the camera in mid-air to see exactly wher I'm going. I can lock on to targets and hit them on the run. I can duck, kick, pick up and throw stuff. And since the skills are progressive, I'm highly motivated to do and find as much stuff as I possibly can. Driving is very satisfying too, once you garner one star (which is cake to do: run over about 10 bad guys, and you're there). The real-time gameplay is several notches above even SA, imho.
The missions are less intrusive, and all seem to come down to find the boss and kill him. Let me be honest: I never finished a single GTA game. Playing though rigid mission scripts, and getting thrown back to the beginning of them whenever I made a mistake, is not at all the type of thing I enjoy about this kind of game. Not only was each mission a sequential chore, but if you get stuck on any one of them, you can't take on any others, and you can't open up the whole city. I thought that sucked balls. In other words, what I loved about the GTAs was the freeform racing and running around, discovering new places, weapons & vehicles, not "completing" the games. Crackdown has no such rigidity on the mission structure. You can go everywhere that you can discover and reach right off the bat. There are places you will not be able to reach until you enhance your agility, but that won't take terribly long. (Since I love hopping across rooftops like the incredible hulk, and I like the scavenger-hunt aspect of finding orbs, I ramped up on that rather quickly. I'm at 3 stars with 90% on the meter toward the 4th star.) You can take the bosses in any order. You'll have a very rough time if you decide to face some challenges before your abilities and arsenal improve, but no one will lead you away from them by the nose.
Oh, and speaking of arsenal, that's another nice touch. Any weapon you find/capture which you bring back to a supply point becomes yours for the asking. You get to select 2 shooters and a thrown explosive device from the menu each time you visit any supply point. This lets you grab the combination of weapons you think will serve you best on each situation. Supply points also act as warp points. You can hop to and from any one you've liberated (visited).
Explosions, gunfire, the tactile feel (rumble), frame rate, graphics, draw distance, speech, etc--all top notch. So is the physical interaction between your character and his surroundings. Everything feels right, the leaps, landings, hanging from ledges, running, aiming, throwing--everything. There's so little to fault in the virtual playpen. The Spanish at least is accurate too. Can't tell about the Russian or Asian guys. Lots of love went into this, and it shows.
It's too bad you can't get the demo, Que. (Although if you get the game anyway, it's a good thing, because the demo gives too much away.) I can't guarantee that you're going to be happy with its enhanced interaction and its more basic mission structure. I am. I want to call up Rockstar and say "see? fun! do this instead!" I guess I'll fall back on the popular phrase. Your mileage may vary.