When it comes to appearance, there's simply no matching concrete in terms of range. You can do anything with it. Mixing blue pigment and broken glass into the concrete can create a luminescent, sealike look. Neutral pigments and river stones can turn a kitchen counter into a sleek dry riverbed. Irregular pigment mixes can mimic granite, marble or any other type of stone. The possibilities are endless, especially when you consider that since concrete is poured into the countertop mold as a fluid, it can take on any shape at all. A concrete countertop can have all sorts of curves and all sorts of built-ins and embedded objects: drain boards, sinks, trivets, knife slots, your old coin collection or even a water feature running along the backsplash.
Granite has its own aesthetic draws. While it doesn't boast the malleability of concrete, granite does have the depth and beauty that comes with natural stone. There's tremendous color and pattern variation both within a single piece of granite and between granite quarried from different parts of the world. You can find blue granite from Brazil, gold granite from Italy and shimmering black from Norway.
And what about that shimmering black -- is it going to show every scratch? In terms of strength, durability and maintenance, there's no clear winner. Yes, that black granite might show scratches, but so might black concrete. Acidic products like lemon juice might eat through a concrete sealer over time. It can also damage a granite finish. Both products are strong enough and hard enough to handle whatever culinary activities you can throw at them. The main utility issue distinguishing the two materials has to do with maintenance. Concrete is a porous material, so it tends to be more susceptible to staining than granite. The sealers used on concrete countertops have not yet completely solved that issue, so concrete will probably need to be resealed more often than granite.
Besides staining, the concrete countertop has been also been plagued by weight rumors. Some claim that concrete is heavier than granite, and that even cabinets that are strong enough to support a granite countertop might buckle under the weight of concrete. But this appears to be untrue. They weigh about the same [source: BobVila.com]. At 1.5 inches (3.81 centimeters) thick, a square foot of concrete and a square foot of granite both weigh in the area of 20 pounds per square foot [sources: Brimo-Cox, NSI]. If your cabinets can support granite, they'll probably survive concrete just fine.
The question is, will you survive?