Why the euro's not so bad

Personally I'd prefer a currency that no government or government-mandated institution could control but failing that, the euro is in fact a much better solution for countries with historically weak currencies than allowing their respective governments to devalue the local currency. John Cochrane expands on that point:

Conversely, and perhaps more centrally, I'm less trusting of the stabilizing influence of central banks. Dispassionate omniscient central banks can, in theory, wisely spot demand shocks and cleverly devalue currencies to offset them, while not responding to supply shocks, political demands, and so forth. The same technocrats could quietly redefine the meter as needed to let tailors respond to shocks without changing prices.

But the history of small-country central banks is not so reassuring. Greece and Italy's repeated devaluations and inflations did not bring great prosperity.

Joining a common currency is a pre-commitment against bad monetary policy as well as foreswearing of hypothetical good monetary policy. Political forces seldom think there's enough stimulus. When Greece and Italy they joined the euro, they basically said, defaulting and inflating now will be extremely costly. They were rewarded for the precommitment with very low interest rates. They blew the money, and are now facing the high costs they signed up for. But that just shows how real the precommitment was.