Just received my packs yesterday. I ordered 2 5-packs for me, and another one for a friend.
After opening my first five, I was starting to get worried, as I had opened 25 packs + 5 seeded packs without getting a single mythic. I was starting to think these may have been mapped.
However, it seems it was just really bad luck, followed by quite good luck. In my second 5-pack I opened a total of 7 mythics, two foil rares (colossus of akros and a foil thoughseize (!!!) ). 2 of my mythics were walkers.
So, basically there's no way the second 5-pack was mapped, so I'll attribute the first one to shoddy luck. Also, the dice are pretty awesome, and it's funny how excited they got me despite being of lesser value.
So, overall, I easily made my money back with my pulls (but that was definitely not my intention), and I'm very happy with what I got. However, if someone gets just one 5-pack that ends up like my first one they may be very sorely disappointed.