I went and saw Titanic last night. The 3-D, as per usual, was take it or leave it; it didn't hurt the film but didn't really improve it, either.
I think Titanic's biggest weakness is also its biggest strength: It's so terribly, wonderfully earnest. It takes its premise, that this is absolutely true love set against the backdrop against the greatest maritime disaster in history up to that point, completely seriously; there's no winking at the audience in this film (at least, not about itself).
And if you can buy into that, if you can accept that creative conceit, then it is a wonderful, beautiful film -- one of the best epic romantic films in history. And if you can't accept the sheer earnestness of the film, then it is one of the most pretentious, self-important POS action flicks in history.