Prozac Pros and Cons?

My husband has suffered from depression/anxiety/panic attacks for most of his life. I was told he was diagnosed with bi-polar disorder but he has never admitted it to me. His mental problems have put a HUGE strain on our marriage (separated many, many times in our 4 1/2 year marriage). So anyway, he has been on Effexor XR for 5 years and now his doctor has changed his meds to Prozac. I'm hoping and praying this new medication will help. Has anyone been on Prozac or know anyone that is on it that can give me some pointers or what I can expect.