If you are considering painting an exterior of your home with elastomeric paint here are a few pros and cons.

Elastomeric coating can be oil or water based. It it is formulated mostly to cover surface cracks and be a sealant against moisture. For elastomeric coating used in residential painting most often surfaces covered are concrete, brick or stucco. Elastomeric paints usually used in coastal communities where waterproofing is desirable, or areas where it rains a lot during the year. Elastomeric paints usually do not chalk which makes them very long lasting. Being long lasting paints, holding the moisture out and hiding the cracks, those are the advantages of the elastomeric paints.
However there are some disadvantages. 
A gallon of elastomeric paint will cover about 80sf per gallon, when most of the paints used for exterior painting will usually give you 200-300 sf per gallon. In addition of covering very small area per gallon, elastomeric paint is  expensive. It is about $130 for 5 gallons, when premium water based 100% acrylic Dunn Edwards paints start at $85 for 5 gallons (all contractor pricing).
Elastomeric paint requires very good surface preparation and high pressure gas sprayer(most electric sprayers won't do the job).
If moisture gets behind elastomeric paint it may become trapped with nowhere to go, blow up like a balloon and the whole thing will come down. If moisture gets behind regular paint, it usually cracks and this crack can wait till next painting job, and be fixed during preparation process.
The cost of painting the house with elastomeric paint will be a few times higher, comparing to best premium water based 100% acrylic paints, and in Phoenix metro with so little rain fall will be hard to justify.