I switched from the pill to Mirena 6 months ago - BEST DECISION I HAVE EVER MADE. Now, I can't say the same for everyone, but I absolutely love it.
I was miserable and crazy on the pill - since Mirena I have felt fantastic. I spot a little every month now - not a full blown "period". The hormones are low enough I don't even notice them. After coming off the pill and doing a low dose cycle I am super happy with my physique, and find that the leanness is much more maintainable than it was on the pill.
My BF can definitely feel it sometimes though - I went back in and got the strings cut as short as they could, helped for the most part but he still gets jabbed occasionally ;-)