I'm not sure I miss anything really, as during the latter part of my religious "life" as a catholic, I went through a divorce, and was made to feel ostracised by the church, rather than supported.
I've since remarried, and my DH and his family are all confirmed atheists. I'd describe myself as either agnostic or spiritual though.
I dislike the thought of organised religion as it causes so many problems in the world, and is filled with hypocrisy. However I do believe we have a purpose, and should do our best to be good people and make a positive contribution to the world and the people around us, and I am very open to the idea of an afterlife. I find certain ideas such as reincarnation and the thought of humanity going through cycles of change, and the part we play in that as individuals fascinating.
I don't miss feeling like a total failure because I didn't let one stupid, untrustworthy man piss my life up the wall because I had mistakenly believed his lies and married him.
I don't miss feeling irritated trying to find sins to confess when I wasn't at all sure I's committed any.
I don't miss the pressure to "put on a show" over religion like the people who never actually go to church but for some reason want a church wedding and insist on christening their children...
I don't miss wondering how the pope could lecture us on contraception and the importance of charity whilst sitting on a goldmine of religious and artistic artifacts, and simultaneously failing to address third world povery and the AIDS epidemic. Although I do actually still feel completely amazed by the hypocrisy of that on a frequent basis.
I could go on, but I will not bore you all!