I think there are more advantages than disadvantages of traveling by plane, because, firstly this is the fastest way to reach far away in short time. 
Traveling by plane is safer than if you travel by car, train, bicycle, whatever ( according to the statistics). 
There are special fares, sales and you could book your e-ticket at low price (that's real advantage). 
And you can feel you a bird or something, watching into the porthole, that's amazing! 

Disadvantages, the prices, sometimes are very high. 
You need to wait for long time, stand in lines, procedure is complicated due to security issues. 
During long hole flights you cannot relax, most of the time have to be seated and fastened. 
Usually not comfortable economy class (depends of air company). Not comfortable restrooms. 
Bumpy happens due to turbulence. 
Some people is sick when a plane is taking off/landing. 
When crush (awful) usually a lot of victims.