I just got a Mirena put in monday. So far so good. Getting it put in was a little uncomfortable, but the whole thing only takes about five minutes, so all in all not really a big deal. I feel fine about the hormone. My midwife told me it's a tiny amount compared to the pill since it's delivered directly to the uterus. Also my midwife tucked the strings around my cervix for me and neither dh or I can feel them.
The only thing I don't like so far is the spotting. My postpartum bleeding had just finally tapered down to an occasional brown trickle and now it's red again. I've been wearing pads or panty liners for two freakin' months!
: I probably could have waited to get it inserted since I didn't get af back with ds1 until he was one, but I just don't want the pregnancy paranoia.
I'm tandem nursing and no supply problems so far.
ETA: I forgot to add that I haven't had any cramping with it at all. I think that's the advantage to having it put in when you're pp.