I love these underwear.  They are don't move or ride up.  They provide good coverage both front and back and are flattering.  I can't say how seamless they really are since I don't own any clothing that would be likely to show seams.  I did have to buy a size up.  I usually wear a medium (I wear a 6 usually pants but sometimes 8) and sized up to the large.  I have washed and dryed them 3 or 4 times and so far they are in great shape.