I think the biggest actual barrier to actually getting one would be having to apply in person, and pick up your card in person.
Certainly for Americans, not a huge number of people will have two weeks spare and sufficient funds to wait for their application to be processed (or the money to fly to Estonia and back twice in two weeks).
Edit: apparently they're "working to add capacity to our embassies to process e-residency applications and issue cards abroad by the end of 2015". This makes the whole thing absolutely amazing. Let's see how the rest of the world reacts, I guess.
Certainly for Americans, not a huge number of people will have two weeks spare and sufficient funds to wait for their application to be processed (or the money to fly to Estonia and back twice in two weeks).
Edit: apparently they're "working to add capacity to our embassies to process e-residency applications and issue cards abroad by the end of 2015". This makes the whole thing absolutely amazing. Let's see how the rest of the world reacts, I guess.