The individuality of kids is fantastic...and hard work.
Our oldest is seven. He's very intelligent and has athirst for knowledge, which is great to see as a parent. The hard part is removing him from his own little world, and keeping up with the constant chatter and barrage of questions. As a baby he was very laid-back, didn't care whether you fed him or not, and slept through everything.
Our middle child is 5. She's "easy-going" to an extent, and clever too. The hard part is motivating her to learn - she's capable but very independant and unwilling to adhere to the "rules" of growing up - getting an education! As a baby, she was a nightmare - chronic colic, she could cry for 18 hours at a time.
Our youngest is 4 months old. She's very easy to look after, and the older 2 keep her entertained. Her downfall is that she's desparate to join in with the other 2, and as a result can get frustrated in the blink of an eye.
Kids huh...we wouldn't be without them!