My children are all within 3 years and 3 1/2 months of age: the first two (both girls) are 2 years and 3 1/2 months apart, and the last two are 1 year and 2 days apart. I admit I was shocked when I found out I was pregnant with child #3. I wasn't upset about having another child - I just really didn't want to be miserable and pregnant again! But that's another story.
Now, I call my youngest two children my "almost twins." Right now, at ages 3 1/2 and 2 1/2, they are almost the same height and weight. My middle child, even at just 1 year old, loved her baby brother from the start, and is very nurturing and mothering. Most of the time. My son, the youngest, would follow his biggest sister around anywhere. All three of them love playing together, and one of the most immediate benefits to home schooling was the increase in closeness between all 3 of them. The few times I've let my girls go spend the night at grandma's house, my son wanders around the house looking for his sisters. Not to say that he doesn't quickly recover and enjoy playing with all the toys by himself.
Which brings me to one of the cons - sharing toys. They are all so close together in age that they all like playing with the same type of toys. If they were further apart, I would imagine that the oldest one wouldn't still be so interested in the "baby" toys that her younger siblings receive as presents. As it is, whenever we get something new for any of them, they all want to play with it exclusively. When I enforce the rules, saying that the birthday boy or girl gets to play with it first, then the others sit there pouting and glaring. When I let the older one have it for a short while during the littlest's naptime, she tends to hide it when I'm not looking and it takes forever to get it back from her. I still sometimes find old infant and toddler toys in my girls' room from time to time. They like role-playing and alternating being the mommy.
I once thought that, to solve the fighting over toys business, I would just buy 3 of the same thing. 3 Hot Wheels cars, for example. No good. It works for a few minutes, but then they all decide that they want to have a matched set, and need all three of the toys in their own little hands. Sigh.
But usually, after a toy looses its "newness," they share pretty well. My middle child is so compassionate and obedient, she tends to give either sibling whatever they ask for, even if it is her own new present! She's outgrowing that some, but still tends to give things away a lot. So does my son, actually, when he's in a good mood. Not when he's not. My oldest - well, she's gradually learning that giving her siblings a toy makes them happy, and that, in turn, makes her happy. She's actually becoming quite good at getting her little brother to stop crying by giving him a toy (he's in the terrible twos stage right now - lots of little temper tantrums!).
For the most part, I love having my kids so close together in age. It makes things simpler in many ways - sharing things, being close to the same stages, and hopefully being able to teach them together for many subjects in the future. The first year of my middle child's life was hard, because I felt miserable during my next pregnancy, and the first year of my third child's life was hard, since I had a toddler and an infant at the same time. (Grocery carts are not designed well to carry/contain a 3-yr-old, a 1-yr-old, and a newborn!) But we're beyond that stage now, and even though grocery store trips are still logistically difficult, everything else is getting much easier.