Ok well I've been playing it a little more now and I think I can comment a little better.
First off, the plot and characters are really incredible. I feel more emotional connection to these guys in 2-3 hours of playing than I felt in the entire game of Mass Effect. Niko is believable and clearly not a thug out for blood. Each character has real personality and that goes a long way with me.
However...the gameplay. It still bores me to DEATH. IT'S ALL DRIVING. Long travel time is why I hate Zelda: Wind Waker. IT'S NOTHING BUT TRAVEL TIME. The ratio of driving/action is ridiculously high. I drive to the mission. They tell me to drive somewhere else. At this point I usually get some action for maybe...a minute. Then I get back in the car and drive again! ARRGH! I DON'T EVEN LIKE DRIVING! Why else would I not have my driver's liscense when I'm 20 years old!? I prefer good old human interaction and movement. I loved Assassin's Creed because just RUNNING was a treat. You could jump and climb and swing and kill at random. Also sorry if I reference AC alot, it's the only other "sandbox" game I've played and I understand it's not the best in terms of sandboxy-ness.
I think I might just not like all the freedom I get. I just don't know what to do with it. I don't want to date really, I already said I could do that same stuff better on the Wii. Eating takes all of 30 seconds. Clothing shopping is for girls. And I'm required to DRIVE everywhere. However I suspect that things might pick up in that respect since I now have Roman's cab service to take me places. And you're allowed to SKIP those sequences. I dunno, it just feels like there's nothing to do. My friend tells me there are no tanks in GTA IV. Couple that with the impossible to control helicopters and the only methods of transport you have are cars/motorcycles on land and like, 2 varieties of boats on water. Seriously, NOTHING to do.
That said the environments are spectacular as well. The people on the streets, the variety of cars you see, the buildings, the weapons. I love that.