Granite countertops are durable and great looking. I wonder if they worth the trouble. Research follows.
Price: granite for countertops costs $60-$120 per sq.ft. with installation, $35 per sq.ft. on sale if you do it yourself. The price includes handling, transportation, and breaking of large sheets. Typical slab from which your granite countertop is cut is 5"x9", but some stone yards will carry larger slabs. It is hard to get figure for installation itself; some manufacturer mentions $250 additional charge for the non-standard cutting of the stone.
Options: not all "granite" in granite countertops is true granite in geological sense. Marble, soapstone, and limestone, as well as others, are used in countertops and floor sometimes for aesthetic reasons. True granite, however, is preferred material for countertops, because it is very hard, resistant to chipping, and absorbs stains and moisture less readily then other natural stones. Granite is not porous and chemically rather inert. Engineered stone is man-made compound consisting of granite chips and epoxy resin. It is even less porous and penetrable by stains when granite proper, but less temperature resistant and cannot possibly look as interesting as natural stone with its veins and irregularities.
Granite countertops are resealed with impregnating sealer every five years or so. All manufacturers and installers I have found, with no exception, claim you should use the most expensive professional sealer, which costs $80 a gallon. A gallon covers about 600 sq.ft. Considering the price of the granite countertop and it's installation, the difference between more and less expensive sealers is negligible.
Care for: granite countertops require certain care. Granite is harder than kitchen knives, and would not scratch easily. However, granite countertops can be stained by food and scratched by some porcelain and glass kitchenware. They say never put anything wet, hot or cold directly on a granite countertop. Stains tend to soak into the stone if not cleaned away. There are special stone-cleaning products on the market, and some homemade solutions, like plaster-ammonia paste to remove oily food stains. No acid cleaners should be used on granite countertops. High polish dark granite countertops will look great -- as long as nobody ever touches them.