I have Mirena. I really like it. No need to worry about remembering pills or shots. I did bleed very heavily for awhile after I got it but I have endometriosis so I don't think most people experience that. I haven't had a heavy period in about 3 months and the cramping I used to experience due to the endo is significantly reduced. I would say it is the easiest and best form of birth control I have ever used.
@daij, I had the paraguard, I had no problems with bleeding or anything else. My cycle was regular and I kept it in for 6 years before trying for our 3rd and was pregnant the month after removing it.