PPO vs. HMO Insurance?

I am trying to understand pros vs cons of HMO vs PPO. We are a family of three (myself, spouse and newborn). We do not have much health issues. Premium difference is about $150 per month (i.e. HMO cheaper than PPO). But need to understand any limitations of HMO. Is it tough to find a PCP who takes HMO insurance? Or is it people with health complications usually opt for PPO as it is more flexible?