That's a good age gap in my opinion. I have that rough gap between mine, and I found it just about right. My sisters are close in age and she's said she wished she had a bigger gap but life is what it is.
We're expecting our fourth and the age gap will be four years. The biggest issue we are having right now is the car. DH and I can't seem to agree on the car. The kids all know #4 is on the way and are excited for different reasons.
After 2, whats one more. After 3, its crazy anyway.