I have the old fashioned copper coil, so no hormones just a metal widget.
As a contraceptive it has worked brilliantly for me, and I love the fact that we don't even need to think about it. Because it doesn't have any of the hormones, I still have a normal cycle. My periods, whilst still heavy, are much more regular and predictable and significantly less painful which is a massive bonus. But there have been some drawbacks:
Like IamMummy, having it fitted was horrific. And this with an experienced nurse both times (once after ds1, but had it removed for a variety of reasons, then again after ds2- I thought it might have been different second time round but no). For me, it really was just like being in labour- the actually fitting bit was fine, lasted 10 mins max and was no more painful than a smear. But the next 12 hours were obviously my womb trying to get rid of the damn thing and it was exactly like being in labour. Established , mind-off-somewhere-else-with-the-pain labour. Then it must have settled into an "acceptable" place and all was fine.
Also, the threads that hang out up there (can just about feel them) are apparently irritating my cervix and I have a very large patch of "erosion" there which does cause occasional bleeding (not spotting) after sex. Two smears have concluded that all is well and that there is nothing sinister about it but I am having a think about whether or not I want it still in there - having it removed last time was absolutely no problem though so at least that isn't a worry.
I would say that my sister also had this same type of coil and had none of the negative experiences- so guess its just a case of trying it out.
Good luck.