I agree with the effect of price in Europe being bigger then other regions, but don´t underestimate the effect of a complete Fifa game on a handheld in Europe, that is a killer app considering how huge that franchise is and it is actually a game that makes sense to be on a portable machine..
Bigger problem in Americas since there will not be a COD game day 1 on the system from what I understand, still the long term potential is big for the Vita
As for the slow start in Japan, pretty predictable if you understand that an Uncharted game can´t push hardware in there (though I think it was even slower then what I thought it would).