The right game at the right price.
The only two ways to lose a life in this game are to either fail to serve a customer before they reach the end of the bar, or to miss a glass that one has slid back towards you, causing it to fall to the ground and shatter. Sending each and every single customer off of the screen will grant you victory in whatever level you are on and send you to the next, more difficult stage. Customers will periodically re-emerge from whatever area you send them to by serving them, meaning that speed is necessary if you wish to progress to later stages. Occasionally, a customer will drop off a tip for your server, which if collected will add both a bonus to your score and set off a stage show which may distract some of your customers and allow you a breather.
Obviously, like most games of it's day, Tapper's goal is to provide hectic gameplay that constantly gets faster as time goes on. In that manner, it can become an incredibly addictive little game as you strive to serve more and more customers and earn higher scores. This need to do better is increased more by the live scoreboards on XBOX Live, which allow you to compare your highest scores to that of the entire XBL user base. There are also several relatively well-placed achievements which challenge you to do better and pull off a few unusual stunts. There are a few online modes, but these really aren't very different from the regular single-player game except that another person whom you can speak with is playing at the exact same time as you and you're both trying to achieve either the highest collective score or outscore each other in that particular match. Not only that, but matchmaking always seems almost totally deserted, meaning that it's difficult to get a match with anyone who isn't a friend.
At 400 Microsoft Points or about five dollars, Root Beer Tapper is a great investment to make on the XBOX Live Marketplace. It doesn't have much to offer beyond the single player mode and very limited multiplayer, but at this price that's really all you need to enjoy this game. Very highly recommended.