Disadvantages:
1) There is a lot of wrong information on the internet. Anyone can post anything, and much of it is garbage.
2) There are predators that hang out on the internet waiting to get unsuspecting people in dangerous situations.
3) Some people are getting addicted to the internet and thus causing problems with their interactions of friends and loved ones.
4) Pornography that can get in the hands of young children too easily.
5) Easy to waste a lot of time on the internet. You can start surfing, and then realize far more time has passed than you realized. Internet and television together of added to the more sedentary lifestyles of people which further exacerbates the obesity problem.
6) Internet has a lot of "cheater" sites. People can buy essays and pass them off as their own far more easily than they used to be able to do.
7) There are a lot of unscrupulous businesses that have sprung up on the internet to take advantage of people.
8) Hackers can create viruses that can get into your personal computer and ruin valuable data.
9) Hackers can use the internet for identity theft.
10) It can be quite depressing to be on the internet and realize just how uneducated so many people have become in today's society.