What type of siding do you have on your house? If it's currently vinyl, you don't need or want this.
You know how if you paint out a thin layer of regular latex paint, you can stretch it a little? That's because the latex has a small bit of elasticity to it. Elastomeric products, such as this one, are chemically designed to have greater than normal elasticity. What that means for the consumer is that if you apply an elastomeric coating to a surface prone to cracking (i.e., stucco, wood, or masonry) the coating will stretch some if the substrate expands. The coating will not crack along with the substrate, so the substrate is not exposed to open air and the cracks don't expand as rapidly. Elastomeric coatings are also generally water-resistant/proof up to a certain number of pinpricks per square inch.
Because of the way they are formulated, they are considerably thicker and heavier than traditional latex paint. 5 gallons of elastomeric might go for $120 at contractor pricing ($200 or more retail) where 5 gallons of a good latex exterior would be $60-80 for contractors ($140 retail). Add in the fact that latex paint can typically cover 300 sq.ft/gallon (YRMV due to substrate conditions) and elasto's usually only cover ~80 sq.ft./gallon and the materials costs add up quickly.
Due to the much higher than normal density of elasto, heavy-duty pumps are required to spray the stuff. You need a contractor with a big dog, like a Graco 200, the kind of pump that can handle 4+ guns with 100' of hose each. That pump needs to have just 1 gun with a short hose to get the proper PSI to spray elasto.
One nice thing about elasto is that many brands are rated to handle lower than normal pH levels. This means you can spray some elastomeric coatings on stucco that has cured for less than the required 30 days and not worry about pH burn.
But yeah, now that you know more about elastomeric coatings then you ever wanted to, I would say 'Don't waste your money'. A good exterior coating like Sherwin-Williams A-100 or Superpaint, Kelly-Moore Color Shield, Benjamin Moore Premium Exterior, etc. will do fine (just stay away from Frazee, their stuff is crap).
