Now there's a report that provides hard data, quantitative data, for how Universal Acceptance is not yet universal and it's got a ways to go. Quote, "The problems identified in the report resulted in a larger than expected number of IDN TLDs being unresolvable, clearly an issue for Universal Acceptance."
From the ICANN and UASG Announce Results of Universal Acceptance Study for New gTLDs --
ICANN, in conjunction with the Universal Acceptance Steering Group (UASG) announced the availability of a new report: An Analysis of New gTLD Universal Acceptance. Universal Acceptance (UA) is the concept of removing all technical barriers that might hinder a user from accessing any name in any top-level domain (TLD) from any web browser, email client, or other Internet application on any computer or electronic device. The report, sponsored by ICANN, is available here [PDF, 1.63 MB].