I wouldn't say that I've had a change of heart regarding Crackdown 2, but rather a change of attitude. It's still not a very good 3rd person open-world shooter, but I think the mistake is on our part, for assuming that it's trying to be.
As with the original Crackdown before it, the game is merely a playground, and the main treat - the collection of Agility Orbs - is the real goal. All the people that you end up killing are merely obstacles in your path. It's sort of ridiculous that such a simple premise can make for such a compelling experience, but there it is.
I do not care about the story or the objectives or anything else - I'm just all about leveling up my dude. I've collected a little over 300 Agility Orbs so far, about 30 hidden Orbs, 5 or 6 of those Renegade Orbs, and so my Agility level is now just over 5. (The gliding ability that I just unlocked is not quite as awesome (or useful) as it could be.) I've started to relent and actually do the "game" stuff as well, if only so that I have more respawn points (such points also let you keep any new weapons you find out in the world), and that stuff continues to be uninteresting.
I'm still of the opinion that it feels more like a huge expansion pack, rather than a $60 retail purchase. If you're a fan of the original, you'll know exactly what you're getting here. If you're new to the series, this is certainly a good place to start, and (probably) well worth a rental.
I also did a little dabbling in Singularity over the weekend, which looks and feels a lot like some sort of high-concept Bioshock mod. (Seriously - it looks just like Bioshock.) It's not bad! It's got some neat time-manipulation puzzle business mixed with all the shooting and the killing. I'm maybe 2 hours in, so I've got a lot left to see, but it's definitely better than I was expecting it to be.