Is it good long term investment to buy bitcoin?
The answer is YES, why? Because now the demand of bitcoin is increasing and a lot of company now is accepting the bitcoin what more in the future so it is best to invest now and hold it in long term.
It depends on the definition of long term. I believe in 10 years, there will be numerous banks providing service based on bitcoin.
10 years are more than enough to wait for an investments based on bitcoin. We just need some 2 to 3 years for bitcoin to evolve itself as a everywhere acceptable payment systems. With that bitcoin investments will hit moon.