I'm not really into computer use that much, don't have internet on my cellphone and don't belong to any social media like facebook, twitter, etc. I've gone several weeks with no computer, TV or cellphone access and only static rare radio stations available when camping in the woods.
I think the biggest negative effect of too much phone and computer use is not with those in our age group, but the children, teens and younger people. Mothers are using videos, video games, TV, etc. for their babysitters. Young babies are propped in front of the TV while the mother is on her facebook sharing selfies.
The kids get no real benefits of the human touch, interactive learning, socialization, real love, etc. Of course there are exceptions of good parenting where TV, computer time is limited and supervised. But, it's become apparent that many teens spend too much time playing video games, and have less life experience in the real world.
Because of this, they lack social skills and empathy for their fellow man (and creatures). Their overall health, mental, emotional and physical suffers as an effect. It seems like many have taken technology that is very beneficial, and have abused it for self pleasure.
Shows like Toddlers With Tiaras and the Kardashians are proof that people are becoming more vain, shallow and self-involved. Some have even committed suicide merely because the stories from their "friends" on facebook were so special and successful, making them personally feel like ugly failures. Not to mention the cyber bullying going on these days.
It amazes me to see people walking with their heads down, involved with the goings-on of their devices, while ignoring everything around them. I personally am glad I never got that involved with the technology. I can walk through the park and listen to the birds or the breeze rustling through the leaves, and don't feel the need to have plugs in my ears all the time.