The Original Tour gives you everything: a 24-hour pass to ride their buses, a cruise along the Thames River, and for an extra 3 pounds, a meal at your choice of several kitschy tourist destinations. That being said, they also give you a fantastic tour of London, too.
Depending on where you jump on and off, the Original Tour will take you past many important sights in London. If you stay on for the entire ride, you will go past Buckingham Palace, Westminster Abbey, Marble Arch, the Globe Theatre, St. Paul's Cathedral, and over the Tower Bridge. Those are just a few of the sights you get to see!
Your trip experience probably depends heavily on your tour guide. Our first guide was fantastic - witty and charming, and threw in tons of tidbits (he knew where the Gringotts scenes from Harry Potter were filmed, for example). Our second guide was still informative, but did not quite have as much personality, so it wasn't as much fun. If you don't like your guide, hop off and stroll around, and wait for the next bus to come by!
Overall, this was a great way to get an overview of London. The buses are easy to spot - who can miss a giant red double-decker? The stops are also easy to spot, as they have their own signs posted.