You can always get a sense of how eagerly anticipated a movie is by the size and behavior of the crowd at the promotional screening. These are held a few days in advance of the movie's opening, and people get free tickets by calling radio stations and such. The promoters always give away more tickets than they have seats, since not everyone shows up.
I showed up 30 minutes early to "Gran Torino" last night and was told the theater -- the largest at AMC Castleton -- was already filled, and they already had turned away 100 people. Probably quite a few more showed up after that and got the bad news.
(Luckily, somebody was doing their job and reserved a few seats for the critics.)
That's pretty astonishing for a January movie. And the crowd was very diverse in terms of ethnicity and age spread. Usually folks under 30 make up the bulk of the crowd.
Based on this, I'm betting "Gran Torino" is going to have a huge opening.