Well, yes, and no. There are sentences one can't utter in public. For example, due to a seldom known and rarely enforced law entitled the "Alien and Sedition Act", it is illegal in the United States to say "I want to kill the President". If someone were to go that far, they'd be abusing the Free Speech clause. Also, it is not protected speech (read: not OK to say) to yell "FIRE!!!" in a crowded theater. Nor can you spread slanderous/libelous rumors about a private individual (Public figures/celebrities are easier to slander, legally).
Now, as for the not being able to abuse said right, for the most part that is true. For example, I can say something like "I don't agree with (insert persons name) opinion. He's full of shit.", and there will be no legal ramifications. As well it should be. I take full advantage of Freedom of Speech, but I also realize there are limits to that freedom. It's not called "Limitless Freedom of Speech, And You Can Say Anything You Want".
To play devils Advocate, though, I'd like to say I've read legal texts which interpret the First as "The Right to Freedom of Press", which is also how I like to look at it. That provision isn't there for private conversations between friends, as they are going to say whatever they want anyway. The way I, and others, read it is that you can verbally say what you want, and there will be no ramifications. However, if you go the extra mile and print it in the local paper/do an Op-Ed on the 11 o'clock news, you better be damn sure you have facts to back it up.
The reason behind this is, if it's just a spoken word, the damage is minimal. It'll eventually go away. If you print it, or broadcast it on TV, it's there to stay. Be it somebody clipping the recipe on the reverse side, or taping the news because they knew they'd be in a "Man on the Streets" segment, the subject of the accusations will not be able to fully escape it. Then your lies come out, and he can rightfully sue you.
Sorry for the rant, guys. But, like I said, somebody had to play Devils Advocate.
Edit: Sly said it best. It's there to allow us to blast the government. Also, I'd like to retract my portion about Alien and Sedition Act, as it's still on the books, but was deemed unconstitutional. Thank you law books...