What tremendously helps is the fairytale, near Disney-like romance plot between the two. It's been a staple of romantic drama for a long time and you'll really root that these two get together as their chemistry is perfectly matched. Winslet is absolutely radiant on screen, and as in all of the similarly plotted stories, it's fun to watch her break free from her societal shackles and cut loose for a while. Likewise, DiCaprio has a terrific on screen charisma mixed with a certain boyish charm. Since the tragic death of River Phoenix several years ago, Leonardo has not only replaced him as the leading teen heartthrob, but he's also turned into quite an actor in his own right.
Slight problems exist, however, with some of the other characters.
To accentuate the class differences, Billy Zane's character and several others are so much the epitome of upper class snobbery that they come off as a bit too calculated. Their presence, of course, is to be Rose's societal burden, but it would have been nice had everything not been so black and white. The story is so compelling and the effects are so grand that they seemingly freeze time. What also initially appeared to be a problem to me is actually a brilliant piece of storytelling by Cameron. What seems odd is that many of the characters seem blase about this.