As an American, I drove only an automatic. Moving to Scotland, I cold only find manual transmissions. The poor guy who sold me my car had to teach me how to drive it. The roads in Scotland are very twisty, very hilly, very narrow, and they have a high speed limit. It felt like a stunt driving track on my commute. I fell in love with driving there and a manual makes it a lot more fun. There's pros and cons though.
cons:
-You can't talk on the phone or drink anything if you're driving a manual through town, you need to use two hands.
-In the first month or two you're learning, you'll sometimes stall the car badly in the middle of a busy intersection, it'll take you a while to get going again, and your fellow travellers won't be forgiving.
-The car will lurch when you shift low gears, so it's not as smooth a ride; you'll get better at doing it smoothly with time, but you'll never be as smooth as an automatic gear change.
-Manuals aren't as good at going very low speeds, like slower than the car wants to idle. If you're stuck on a highway and traffic is moving less than 5mph, you kind of have to drive with the clutch half-way pressed the whole time.
-Manuals are harder to find so you get less consumer choice. I just bought a car, insisting I wanted a manual, and <1% of the cars on lots here (wisconsin) had it.
pros:
-A manual lowers the price of your car.
-You can get better fuel economy than an automatic by shifting early.
-You can accelerate much more quickly by shifting late.
-You can shift pro-actively instead of just reactively. You can downshift in anticipation of that big hill ahead.
-Non-Americans won't think you're such a lazy bum.
Final pro: A friend of mine had his Jeep nearly stolen. It was found 10 feet in front of where he parked it with the doors open. A witness said the thieves broke into his car, got it started, tried to take off, and had to abandon it because they couldn't drive a stick.