Just to sort of put things in perspective, here's how things work in my house.
I've got a 5 (almost 6) year old and a nearly 2 year old. My 5 year old is in kindergarden and at the beginning of the year was testing out at nearly 1st grade levels. She's not ready to skip a grade but she's quite advanced. We're working on reading and basic math stuff.
We've got a tablet in our house (an iPad) and gets very limited, but purposeful by her. On the weekends we'll leave it out for her to grab in the morning and watch cartoons on. She normally gets up at 6:00-6:30AM on Saturday and Sunday and if she grabs that when she wakes up she'll stay in bed until 8:00AM when my 2 year old is ready to get up and leave my wife an I a bit more sleep. It's selfish..but she's happy. We're happy and it's a win all around.
On weekends/days off from school she's still to the age where she really *needs* a nap in the afternoon because she just wears down. But she doesn't want to take one. So instead of fighting that battle she can go crash on the couch and play some state maps, or angry birds or whatever for an hour or so and just sort of chill out and recharge. She also likes to flip through picture albums we have on there of family and places we've been on vacation.
As she's starting to get more and more into books I'm looking into options to make books more portable and easy to read. I'm not sure if you guys have priced books lately but they don't give kids books away. These things add up in prices. Plus with a 2 year old in the house it's hard to keep them out on shelves because they just get pulled off and destroyed. The idea of a kindle and a book subscription is intriguing and worth looking into. There's a pile of stuff that is easily available to download and read. We've gone through a lot of the books that our modest local library has and our own books shelves have been read through dozens of times and a little stale.
When we travel the tablet is nice for road trips. My 5 year old has been to about 20 different states. My 2 year old to about 10 different ones. We get out and travel a good amount. The tablets are nice for tossing the back and keeping the drive more peaceful. She can color on there, work on puzzles, play games, watch movies. Whatever. It's a lifesaver. Plus when we get into wherever we are going it's a good babysitter for a little bit while we get unpacked and settled in.
We watch very little TV in our house, tablet use is highly monitored and it's just one little tool in the bag that we use to keep everyone happy. We still spend *a lot* of time outside. We've got memberships to the local zoo and science museums that we frequent multiple times a year. We travel a lot. Tablets for us are just a little bit of extra free time on the weekends to catch some sleep, get dishes done, get a few extra hours on the road, ect. They are versatile in content, easy for kids to use, get great battery life, and offer utility to us once we get to where we are going.
They aren't replacing outdoor time, coloring books or legos. We've got lots of those. It's just a supplement to those.