Greece problems ran deeper than just entering the Euro, massive corruption and tax avoidance played a major role creating that crisis. Its estimated that ~25% of the Greece GDP where not subject taxed, effectively a shadow economy.
It's worth noting that when a country has control of its own currency, its issues are more self-contained. It doesn't get easy money based on the performance of other countries within the EU. It also can devalue its own currency if it can't pay back its own bonds.
How about Italy and Portugal then? The truth is that the Euro was a political decision with disregard of ecomics. That's why Margaret Tacher refused to adopt the Euro for the UK and warned that it would end democracy in Europe.