It's funny. What more could one ask for?
Tina Fey and Steve Carell play Claire and Phil Foster, a staid married couple from Teaneck, NJ. They're shocked when their married friends announce an impending divorce; they resolve separately to inject some romance into their own relationship. Claire dresses up for their traditional weekly "date night"; Phil resolves to take her to a trendy Manhattan restaurant instead of their usual family-friendly joint. But things go very wrong when they poach a reservation from the "Tripplehorns", which (in turn) causes two thugs to shake them down. And things escalate from there.
This could have been lifeless and drearily formulaic, but Mr. Carell and Ms. Fey really do a good job of making their characters (if not the plot) believable and sympathetic. And Ms. Fey is, as always, a dynamite combination of smart, funny, and pretty. ("Why, if I were twenty years younger… and unmarried… and better looking… and more interesting… and richer…")