Most consumers are aware of fiberglass batten insulation. That is the pink or yellow stuff that you see when you open a wall. This type of insulation has a paper backing that allows it to be easily rolled between wall studs. Fiberglass insulation has an R value of around 13 when placed in 2 x 4 walls.
Foam insulation comes in two varieties, open and closed cell. Closed cell foam insulation is much denser than open cell, and not only require more expensive material, but it also is more labor intensive to install. This later point is due to the fact that closed cell foam insulation has to be applied in thin layers. If the layers are too thick they will not dry properly and off-gas.
Closed cell foam insulation has a much higher R value than other types of insulation (R 7 for every inch of thickness). In practical terms, it will yield a total R value of 21 for your typical 2 x 4 wall.
However, there is another reason to use closed cell foam, especially in walls that have a clear access to the outside. My customer chose to use this type of insulation as a barrier in his garage, as he had a mouse infestation problem. Mice can easily create tracts and nests in fiberglass batting.
Installation can be done in less than a day (depending on the area). I advise the customer to be out of the house during installation. They can safely return home by the end of the day.