i've watched both willian and eriksen probably 6/7 times now. willian has been very impressive, he's quick, the ball seems to stick to his feet, moves around the front 3 positions fluidly and the one thing that surprised me about him is that he works pretty hard off the ball, usually with these "types" of players they'll lose it and stroll back but hard work off the ball sems to have been drilled into him and the rest of the shakhtar players. the 4 goals he has in the cl this season have all been taken very well.
eriksen on the otherhand was practically invisible for denmark at the euros, for ajax he's been a little livelier but i haven't seen much evidence for the hype he's been getting over the past couple of years, it is a very small sample size though so i could well have just caught him on off days. he reminds me a little of sigurdsson.
Eriksen is a really really talented player, and is probably one of - if not - the best player at Ajax atm. The problem he has when he is playing for the national team, is that people expect him to be the center of everything and he is simply not good enough to do so yet + he has way more technically skilled players around him at Ajax. Keep in mind that he is only 20 years old.