Do hybrid suvs really work? Do they get as good gas mileage as they say? Are thay as clean as they should be? Do many people buy them?

This is a question to see if there are good points to owning an suv hybrid or not. Here is a list of Hybrid suvs currently on the market.

http://www.fueleconomy.gov/feg/hybrid_sbs_SUVs.shtml

Future hybrid suvs

-Audi Q7
-Cadillac Escalade
-Chevrolet Tahoe
-Dodge Durango
-GMC Yukon
-Porsche Cayenne
-All new Toyota Highlander

Also, GM's hybrid trucks. Are those really any good? Will the GMT900 hybrids with V8s be a hit? To make things short, Are hybrid suvs worth the money or not?