I've been meaning to get this posted but haven't had a chance until now. Not all rivet transfers are made equal! I've been using Archer transfers for a while and love them. The variety of sizes etc. available are excellent. The Archer transfers have a much nicer three dimensional quality to them compared to the MM ones.
Take a look at the following high resolution scan of the MM product. This hasn't been altered in any way and the product was straight from the package. What is decieving about showing far away shots of the MM product is that there are massive variations in the resin vs the printed (black) details. You can somewhat see this on the image that eTraxx posted. Basically, the black printed lines/dots are nice and clean but the resin is a mess. When you prime/paint your model w/ the MM details, this is a huge problem as the rivets are only half there half the time.
I'm guessing MM just started making these and haven't got the technology working 100% correctly yet and the resin is distorting after it's laid down. Hope this helps someone who is looking at both trying to decide.