Bikram's yoga series is 26 asana designed to stretch muscles, ligaments and tendons. It also moves fresh, oxygenated blood to each limb of your body and discharges most toxin in the body to maintain good health. Dedicated practitioners maintain a proper weight while developing muscle tone. Each posture in the Bikram series was included to work the body from the inside out.
The practice is to do the 90 minute series in a hot room (room temperature is on average 90-110 degrees Fahrenheit). The purpose of the hot room is to give the body more freedom to release into the postures.
This is important because each pose is dependant on the ones that come before it. Each pose prepares the body for the following posture. It is scientifically designed to warm and stretch muscles, ligaments and tendons in the order in which they should be stretched. To start in the middle would be a shock to your body.
Bikram's philosophy is based on doing the posture correctly, not how quickly you can force yourself into the posture or how you can jimmy your body to get into it. Your progress is dependant upon your honesty with with yourself.
In Yoga there is no standard of comparison except yourself. In Bikram Yoga, you can receive all the benefit without perfect extension of the posture. The benefit of each posture is automatically there, even if you are far away from the ending form of the pose.