The biggest surprise in this movie was an amazingly good performance by John Stamos. With 2 icons like Matthau and Burnett, you would expect that it would be their performances that would carry the load, but it is actually the relationship between Matthau and Stamos that is at the heart of this story.
They have a wonderfully natural chemistry together, I'm betting that Stamos was in awe of the opportunity to work so closely with a master like Matthau and it was likely that closeness that drew out such a great dramatic performance by Stamos.
Burnett is great as always, but her role is quite subdued and the real magic in this movie takes place in the exchanges between the 2 male leads. Terry Polo also gives a nice performance here.
All in all this was a satisfying watch. A very simple story but acted with such a natural credibility by the ensemble cast and an intelligent script that it is elevated to being much better than average.