In Dinner for Schmucks, most the humor was built around making situations more and more over-the-top. If you ask me, that’s a pretty cheap way to do a comedy (see Meet the Parents). It ignores the need for witty dialog, the element of surprise, or clever writing.
This film definitely had some funny moments scattered throughout (in the few places where it didn’t just rely on its pure silliness), but it was difficult to contextualize these moments or to care about the movie as a whole.
To sum up my very short critique, I wouldn’t recommend this movie. It wasn’t horrible, but it wasn’t good. I don’t know what else to say about it. It was perfectly underwhelming.