I love bands for many reasons. They are portable, easy to store and carry on trips, very versatile allowing an almost infinite number of exercises, and relatively inexpensive. Bands can be used with weights as illustrated in the videos below, or they can be used without weights very effectively as well. This article explains their value in increasing the Rate of Force Development (RFD) as well. I don't particularly think there is any disadvantage to using weights, but I think bands can be a great adjunct and even a substitute when traveling or when weights are not available. I always take a set of bands whenever I am traveling or away from the weight room. My two sons and a daughter all served two year missions for their church and used bands during that time. They returned with a pretty high level of strength in spite of not spending more than 30 minutes a day exercising. I don't get carried away trying to determine the exact resistance. I just use thicker and/or multiple bands to find a resistance level that is appropriate. You can mimic most of the standard movements like presses, squats, pulls, and rows as well as doing movements at angles that are not possible with barbells or dumbells.
Many strength training programs focus on developing strength before speed or explosiveness because strength is a precursor to explosiveness. Explosiveness will improve as strength improves. This is the approach we take in strength and power sports at Athlete Physics. Much of the speed and explosiveness improvements come from the athlete intentionally thinking about lifting the weight as fast as possible.
However, one downside of this approach is that weight or resistance remains the same throughout the entire range of motion (ROM). For example, think of the Squat. The hardest part is at the bottom, while the top is easy. The easiness at the top of the Squat means an athlete is no longer driving the weight as hard as possible; therefore, that athlete is not becoming as explosive as possible.
Few training methods exist to ensure athletes are developing explosiveness throughout the entire ROM. However, adding resistance bands to barbells can overcome this shortcoming. This method of training includes using thick elastic bands in combination with traditional weight for resistance.
As the elastic bands are stretched near the end of ROM the resistance gets harder, ensuring an athlete continues to drive as forcefully as possible. A study at the University of Louisville compared light/fast Squats, heavy/slower Squats and Band-Resisted Squats with moderate weight. The Band-Resisted Squats were shown to improve strength equally to heavy Squats and improved power better than light/fast Squats and heavy/slower Squats.
So what does this mean for you? Because the Band-Resisted Squats improved strength just as well as heavy/slower Squats, they are likely to be applicable for both novice and advanced athletes.