Honestly it depends on the kid. I've got two kids and this summer the oldest (girl) is 4.5 and my son is 1.5. At times it's great but other times it's a 4 person job. Some kids are super easy all the time but the reality is it's anyones game in the woods.
The first year with kids has always been the easiest for us. They nurse, they don't go anywhere and they sleep pretty well. The second year on is tougher because they have habits and comforts at home that unknowingly (to everyone) they can't really be without. Sleeping is more of a chore as are naps in a hot tent.
My kids are great eaters and while camping they tend to graze all day so set meal times are a little hard to plan for. If you've got a meal that takes concentration or a lot of input your child may use this time to wonder, hurt themselves, decide to melt down, etc.
We pack twice the number of clothes, diapers and wipes we think we need. Hot clothes, warm clothes, additional shoes and all the medicine you think you might need at home. My daughter has a pretty bad reaction to camping mosquitoes and without some OTC kids meds she's miserable. Diaper cream, sun screen, bug spray, eye drops, nail clippers, etc. We camp many times throughout the year (hot, cold, tents, cabins) with both kids and we've needed everything. In the end it's easier to pack it just in case.
We tent camp at campgrounds and boon dock it. We are usually near water which is nice for all the obvious reasons. Shade shelters and packn'plays are nice for sleeping, naps and containment time. Toys, books, scavenger hunts, etc are great to pass the time and make the traveling easier. The moms get a lot of kid ideas for games, activities, crafts, meals, etc on Pintrist. Our second trip this year was with 8 families and 16 kids total for two nights. There was a lot of planning and in the end each family was only responsible for one meal the entire time, huge life saver.
It also helps camping with another family. Even if the kids don't know each other they'll have a blast. I grew up in a family "play group" and we camped though high school with all the kids and families. I find it more challenging to travel with folks who do not have kids than traveling with just our family. When you're with others that know what you're dealing with and/or know how to help it makes everything go so much smoother.
It's also a good idea to know where you'll be camping and have an idea of what you want to do. A hike, swim, paddle, etc. Idle times make the kids bored and fussy. Bring some comfy shoes as well. I haven't used our camping hammock once (set it up every time) and my new chair isn't even broken in. I'm up playing, wrangling, making bathroom runs, dishes, etc.
