We've been during Easter. Hubby is a teacher so our time to vacation is limited. Yes it is crowded, but if you plan and "go with the flow" you will still have a great vacation. If you have never been it will be overwhelming, but if you are a frequent visitor you won't feel it quite so much. I would avoid MK on Easter Sunday. We've done it but we just stayed awhile and park hopped. Also if you are planning on eating anywhere in the parks on Easter Day make PS ahead of time. Also be warned that many popular restaurants adjust their menus on Easter (i.e. raise the prices and offer a wee bit more!). Plan accordingly. As another poster has said, the weather is perfect at that time of year and heck you're in Disney, so what if it's a little crowded!! My favorite memory is walking along with the mob towards Splash Mountain and hearing my name yelled by a woman I know from home. She has a VERY loud and distinct voice. We just laughed and laughed, where else could you be in the middle of tons of people and run into someone you know! You will have a blast. Go with a good attitude, be flexible, and let the magic happen!
Have a Wonderful Vacation!!