I have turned more people on to Crackdown than I can count. I too thought it would suck but it is awesome for sure.
Go to Los Muertos first, stay there for a while, one on the Agency tank cannon car and one on the Agency SUV. Just keep hitting the gangs but don't take out the underboss. And steal all the gang cars first, take them back to the Agency garage for points before you wipe out the gang. The hardest car to steal is the airport luggage car on top of the oil rig in the Volk ocean where the boss is. Don't ask me why it's there, and it doesn't show up until you kill the boss. Some tips for the Confiscator achievement. There's a boatload of tricks on youtube and on crackdown.wikia.com
Don't forget to get the 800 round Harrington from the Volk, and the Firefly from the Shi-gen. Once you have those two, your set. And the Firefly makes it easy to do Body and Car Juggler. Good luck, and don't say I didn't warn you that HOURS will go by once you get hooked on Crackdown. Made by David Jones the same guy that invented GTA. Oh and go to settings and crank up the music then, when you get out of your vehicle, stand next to it so you can hear tunes while your path of destruction continues! :)