Hi Doobs, I had a Mirena fitted about 3 years ago and wish I had had it sooner. Apart from brief spotting for the first couple of a months, it has been fantastic. Periods have almost disappeared, I can't tell it's there and have to keep reminding myself to check for the strings like I'm supposed to! My friend had the normal copper coil fitted & had endless problems, including REALLY heavy periods, she's changed to the Mirena & has been fine since.
It DID hurt slightly when first fitted but nothing I couldn't cope with.....make sure you ask for the anesthetic gel when they fit it.
No problems at all during sex!!