Old World Blues is add-on content at its best.
A radio broadcast on your pip-boy invites you to a midnight feature at the Mojave drive in. The next thing you know, you wake up on the balcony of The Sink, your-soon-to-be home and shelter for the remainder of the DLC, and even after that. You find that the think tank, a collection of pre-war brains preserved in robotic bodies, has captured you and taken out your brain, heart, and spine. Except, they have no idea where your brain is. They are surprised you have any intelligence, and then quickly enlist you to help them defeat the seemingly evil Dr. Mobius by telling you to find the three technologies hidden somewhere in Big Mt.
The story is fresh and exciting and will send you through the world of Big Mt. (a.k.a. The Big Empty) to collect new and exciting technologies while fending off Lobotomites, Cyber-dogs, Nightstalkers, Cazadores, Robo-scorpions, a variety of other robots, and even your old friends from Vault 22. I found a lot of new things that were all extremely useful, including a glowing blue halo that regenerates health constantly and a kick-ass proton axe.
You even find some holotapes that have the voice of Ulyssess, the other courier six, and find some hints as to what he was doing in the Big Empty. Another thing you should note is that this add-on is very, very humorous, and I even caught myself straight out laughing a ton of times.
You also have these these robotic appliances in The Sink, which, if you find the right holodisks around the Big Empty, will have their own personalities and can provide their own services. (The toaster and Muggy are easily my favorites.) You can even change around your entire appearance if you fully upgrade the auto-doc.
However, all things have problems. Old World Blues handled quite well compared to the buggy main game, however there is something missing that you can just feel. The length of the main story is a short three to four hours long, not counting the first scene of dialogue, with the large amount of other content seeming to be a little rushed in. As I just mentioned about the first scene, the dialogue can drag on for very long amounts of time. (I don't find this much of a problem, but many may be annoyed by the fifteen to twenty-five minute conversations you have. There aren't many times when you are actually talking, however, making it more tolerable.)
All-in-all, Old World blues is easily one of the best DLC experiences I have had, not only with New Vegas, but ever. (It is, indeed, right up there with the amazing Point Lookout)
If you have the $10, buy this immediately. Seriously, go get it. Now.