The advantages are wide and varied depending on your current outlook on life: research can be a huge part on internet use, knowledge storage and transfer can also be a big part of the internet, intertainment, idea sharing. Coming from a time before personal computers and the internet I think it can be great for all ages
The disadvantages are the same as for advantages. The old adage applies, "Buyer beware". Remember that all people have biases and that many have agendas, don't take what you see on the internet as fact. Verify, verify verify!!!! Another old adage comes to mind by Benjamin Franklin, "Believe none of what you hear and half of what you see.