Michael Mann, a spokesman for EU foreign policy chief Catherine Ashton, said of the talks: "There is a positive atmosphere... contrasting with the last time."
The BBC's James Reynolds, in Istanbul, says the envoys had earlier set the bar pretty low - saying they did not expect detailed, substantive proposals from either side.
What they wanted to see, he says, was whether Iran was ready to seriously engage and, if that happened, there might be another round of talks in four to six weeks time.
Ah, by going well the Euros mean that the Iranians haven't screamed in their faces and may agree to meet again in a month or two. Iran can keep that up forever--or at least until they get nukes. And sycophants here will praise President Obama for the mere existence of talks.
And the Obama administration will be happy to pretend all is well as long as the stretched-out, low-bar talks keep going at least until mid-November. Avoiding challenges from our enemies over the next half year seems to be the priority of our foreign policy these days. And we'll give a lot to buy that space.
If Iran is acting nicer, it is because they feel they need to prevent an attack on their facilities. The question is whether they are closer to a nuclear capability than we think, they are just buying time regardless of how much they need, or they expect President Obama to have more flexibility to give ground to Iran after the November presidential election year.