My kids were on tv-diet for about 5 years and it was overall very positive experience. There're several things here:

a. TV (and other one-way information sources) is really bad for babies/toddlers who need two-way interaction with the world.

b. for older kids(~4y+) replacing regular TV channels with dedicated documentary/learning videos in reasonable quantities is beneficial.

I'm quite curious on how virtual interactions(ipad/etc) affect child development, any research links?