Copper IUD - is it worth it??

I had the Mirena for a year and just had a terrible time with it. Weight gain, acne, mood swings, etc. I loved the protection but it just wasn't worth it! I'm on a low hormone pill know but want to know more about the copper IUD. I would love to be hormone free but I've heard the periods are awful. Are they monthly? I have light periods as it is. Help, i need the scoop and opinions!