The most important feature of a good smoking pipe is a free air passage from the bowl to your mouth. As you examine through the endless examples of pipes at your favorite shop, check the airflow by inhaling the pipe as you would if you were smoking. The passage should be clear and the airflow unrestricted. A whistling sound may indicate an obstruction within the air passage or a joint that is constricting the airflow. Any restriction of the airflow will make it difficult to keep the pipe lit. In addition, because you have to puff harder to keep the tobacco alight, heat will build up rapidly in the pipe and result in an uneven burn of the tobacco.
Other major considerations in purchasing a pipe are balance, weight and bowl size. How a pipe balances in the mouth is important. Avoid pipes that are too heavy or out of balance. A poorly balanced pipe or a heavy bowl can lead to sore jaws and teeth. A new pipe in a shop may not seem heavy or unbalanced at first, but handling it for a short period of time before purchasing should give you an indication of how the pipe will function in the mouth.
Bowl size is equally important. People have different requirements for bowl sizes and shapes. Many people prefer larger bowls because they smoke cooler. Others favour small bowls because the pipe fits into their pockets and purses. Larger bowls weigh more and can unbalance the pipe as well as weigh on a jaw. Larger bowls are often enjoyed by tall or larger people while Europeans, ladies and men of smaller stature tend to cater to smaller bowls. Conversely, conventional wisdom has it that round faced smokers prefer straight stem pipes and long, narrow faced folks tend to smoke full bents. The list goes on and on of matching personalities, sizes and shapes of pipes to people. In short, choose a pipe that appeals to you, feels right in the hand, compliments your facial features and looks handsome to smoke.