I've got a Mirena coil, which had been great. Very light periods, can mostly forget it's there. I had the implant before which made my periods very irregular, which drove me nuts, but I seem to be on a regular 28 days with Mirena.
Having it put in was less than pleasant, but still nicer than the implant!
That being said, I could't find the strings recently, and had to go back to clinic for a check-up. It was worse than having a smear done - very unpleasant! And since the doc couldn't find it I had to go for an internal ultrasound, which was better than the internal but also not something I'd suggest for a fun morning out!
I think my doc cut the string a little short when she put it in, though, cos I've always only just been able to feel them. So I don't think losing the strings is a common thing.
Otherwise, I'm very happy with it. No remembering to take pills, no nasty condoms, light periods, all very simple!
I do worry that the suction of my mooncup will pull it out, though!!