For me, it's every bit as addictive as World of Warcraft or any other MMO I played was.
I have the ultimate defense against MMO addiction: MMOADD. Massive multiplayer online attention deficit disorder.
Grinding? No thanks. Doesn't hold my attention.
Questing? No way. You kill your own 789475938475 snow moose to get 4 pelts and make your own frozen armor +1...or whatever.
Instances? Nope. Can't block off 4 hours of my day to play through an instance. At least, not without upsetting my wife. Happy wife, happy life.
SIDE NOTE: My wife is awesome and lets me spend a fair amount of time playing games online, but I agree that 3-4 hours straight of online gaming is too much for the average married person (unless, of course, the person's spouse is running the instance with them, which, from what I hear, is more common than you'd think).
PvP? Sure, I'd love to...if I didn't have to grind, quest, and run instances to get the gear I need to survive long enough to land a hit on the opposing team.
Auction House? Okay, so you found my one weakness--but even that didn't last for more than a few weeks.
But enough about WoW. This thread about AC:CF and I'll bring us (nearly) back on topic.
I liked AC:WW. I really did. It was like portable therapy. As an unemployed man in America, it can be frustrating to make calls, send e-mails, interview for jobs, and at the end of the day still be out of work. All that effort ultimately results in no visible benefit other than aversion of guilt.
A game like AC:WW (and, by extension, AC:CF) allows a player to immediately see progress, whether that's in the form of a few more bells paid toward one's mortgage, adding a new fossil, fish, or insect to the museum, or collecting another K.K. Slider tape.
AC:WW is calming and I assume AC:CF will be the same. And while I appreciate the relaxing nature of the game and would even recommend the game to others with expendable income, AC:WW didn't offer enough to hold my attention.
I don't think it's anything wrong with the game. I also put Xenosaga down after a few hours because all the cutscenes were getting on my nerves. (Seriously, is Xenosaga a movie or a RPG?) I wish AC:CF added more to the AC formula than it does, but even then it probably wouldn't hold my attention for that long.
In short: "It's not you, it's me." AC:CF looks like a great game. If you have $70 to spend on the WiiSpeak bundle and still tithe to your local church and pay your bills, then read the reviews and consider a purchase.
I'm not really sure why I typed all that out. But since I did, I might as well end with this: MMOADD, or gaming ADD in general, might sound like a bad thing, but it's actually very helpful when one is the President of a gaming group and also President of an Alliance of gaming groups. I like to stay "in the know" and that means playing or at least researching a wide range of games.