Here is a plot I made showing which seeds advanced to the round of eight (green), eliminated in round of 16 (blue), or eliminated in the group stage (black).

Some thoughts:

• The only group that didn’t advance anyone to the final 8 was the “group of death”, group F.  France, Germany, and Portugal all lost their games in the Round of 16.  That’s the last two World Cup Champions and the last Euro Champion all eliminated.
• Of the 8 teams to advance, three of them finished third in their group.
• One 3 of the 6 group winners advanced to the Quarterfinals (England, Italy, Belgium).
• Groups A, B, and D each had two teams advance.
• Belgium and Italy who play each other in the Quarterfinals combined for 6 wins, 0 losses, 0 ties, and 18 points in group play.  The other 6 teams earned 26 points TOTAL from 7 wins, 7 losses, and 4 ties.
• Two teams in the final 8 had two losses in the group stage (Denmark and Ukraine).
• There were 7 teams that had 0 losses in the group stage.  Only 3 advanced to the Quarterfinals (Spain, Belgium, Italy).  And all three of these teams are on the same side of the bracket.
• If you are wondering how the matchups in the knockout stage were decided, check out this wikipedia page. Cheers.   And go Denmark, Switzerland, and Czech Republic!