We got ours when my kids were 7 and 10. The hardest thing was keeping the floor clear of things (toys) that couldn't be eaten. My pup wasn't a chewer at all. But I did worry that he would think everything was edible.
I got a playpen so that if I needed to do bedtime etc (pup wasn't allowed upstairs until toilet trained) then I could put him somewhere safe without having to make sure all things were picked up.
Also my kids were so looking forward to walking the dog. But the reality was that for the first 6 months walking him wasn't as much fun because he needed to learn how to walk on the lead, not eat all the leaves, recall etc. At times at the start the kids found that he 'spoilt' our usual relaxing walks.
Toilet training means going outside every 20-30 mins or so and then waiting for pup to wee. Which meant I had to leave the kids inside at times while I was in the garden. Not a problem with ages 7 and 10 but with younger kids that could become tricky.
Not to mention the puppy razor teeth, cleaning up accidents on the carpet, not being able to go out much at all ever for the first few months. My pup was actually easy considering how they can be. He wasn't a destroyer and wasn't a big biter either. I can't imagine how we would have managed if he had been!
Saying all that my kids adore him. He's now very much a part of the family and fits in brilliantly. My youngest in particular adores him (more than she does me I think!).