Credit Cards are a really good way to start building credit if used responsibly. Because I had a Credit Card for a couple years and always payed it off on time my credit was in great shape when I applied to rent my first apartment and buy my first car. This allowed my to get both without a cosigner and with a very low interest rate on the vehicle, a lot of my friends with bad or little credit had to get their parents to cosign on their first place and pay higher interest rates on their cars.
The problem with credit cards is that a lot of people use them to live beyond their means, it's easy to say I really need this new shirt and even though I don't have the money for it yet I'll have it when the credit card bill comes due, then when the bill comes you've spent the money on something else, can't make the full payment and start the wonderful process of paying very high interest payments as your debt continues to expand due to all those other things you must have but can't afford because you still have that initial debt from that shirt to pay off. Also if you screw up and send it a payment late they'll hit you with a late payment fee as well as interest.
So in short: get one if you can, use it very sparingly at the beginning and ALWAYS make sure you have more than sufficient funds in your accounts to cover your purchases. Also if your credit card is stolen it's much easier to dispute fraudulent purchases than with a debit card, and unlike debit you aren't out the money until the bank re credits your account.
