In Life as We Know It, Katherine Heigl and Josh Duhamel discover that their closest friends have appointed them guardians of their child in the unlikely event of their joint death--an unlikely event that has just happened. Make no mistake: There's no reason this movie should have been any good. The premise is the worst kind of formulaic Hollywood claptrap; the pleasant but cautious Heigl (Knocked Up) is playing yet another uptight fussbudget; since a promising movie debut in the underrated Win a Date with Tad Hamilton!, Duhamel has largely coasted on his looks in tripe like the Transformers movies--yet Life as We Know It is surprisingly likable. After the movie gets through the basic exposition--and navigates some radical shifts in tone with unexpected deftness--the script somehow manages to make its clichés into something resembling real human situations. The colorful supporting characters are all entertainingly written and well played by a solid cast. And both Heigl and Duhamel give understated, engaging performances that manage to make the inevitable conclusion seem almost not inevitable. Director Greg Berlanti (The Broken Hearts Club) deserves kudos for skillfully balancing humor and pathos and turning this unpromising material into a sincere and enjoyable movie.