Yes, like everything in life there are pros and cons to it. If you are male you get a third less risk of heart attack due to iron loss in donation, but not if you are female, I am sorry to say as they have a menstrual cycle. You also get a free tea and biscuit, as well as the medals they give. The only disadvantage is that it can take a long time, over an hour in some busy sessions, and you are not allowed to have drugs like aspirin five days ahead. If you love doing that much you can also give blood platelets like I do, but ask the NBS staff there. For more details see below:
www.blood.co.uk/platelets