Whoever said starting your car burns a lot of fuel is a complete moron, and his opinion should be taken with a grain of salt from now on. Shutting your car off will most certainly save fuel, however this savings is generally NOT worth attempting in a standard mechanical driveline vehicle. Your starter won't last as long, that's a gaurantee. However, whoever said you'd have a dead battery after a day is also wrong, generally. Unless you are a UPS package car who travels 50 miles a day, making over 150 stops a day, your battery will probably be fine. Again, these are generalizations. There are limits to everything, and without knowing your exact situation, I can't really advise you anymore. If it were my car, I wouldn't bother with it because I only drive about 10% city, and that would get really tedious.
Edit: I just read someone else saying it's harder on your engine. The only time that's true is if you do a ton of starts and stops before the engine gets warm, and even that isn't a big deal with gasoline engines. It's no extra wear and tear.