When Germany converted to the Euro, the conversion rate was (IIRC) about ~2 DM to the Euro but from what I recall, a lot of everyday things went from costing 7 DM to 7 euro, effectively doubling in price. IIRC France was similar (ie ~6.5 francs to the Euro but 10 Francs went to 3 euro, etc).
I've tried searching for any studies on this to see if the effect was measured and, if so, whether it held with later countries joining the euro.
I'm a little surprised that the euro has been this stable for this long (going on 30 years). Finland debated leaving. IT's debated if there's even a legal mechanism to leave. We still have the problem that the ECB sets eurozone monetary policy with Germany and Greece being vastly different economies.