It was a masterly takedown, as he ran over the points raised by the Greek side and demolished every single one. Bascially, Greece had undertaken in 1995 not to block Macedonia from joining international organisations under the name of FYROM, and had broken that undertaking in 2008, and no amount of obfuscation could really get over that fact.
The Greeks are claiming partial victory in that the Macedonian request to the court that it prohibit Greece from doing the same thing again was rejected. But the Court's actual verdict offers them little comfort; it is clear that the ICJ expects Greece to do the right thing and allow Macedonia to join NATO (and, by implication, start EU membership negotiations):
...the Court does not consider it necessary to order the Respondent, as the Applicant requests, to refrain from any future conduct that violates its obligation under Article 11, paragraph 1, of the Interim Accord. As the Court previously explained, “[a]s a general rule, there is no reason to suppose that a State whose act or conduct has been declared wrongful by the Court will repeat that act or conduct in the future, since its good faith must be presumed”[.]The Greek government at present is not in a strong position to do anything, but this is a very strong judgement, and one hopes that it will create space for some sober reflection in Athens. (Alas, NATO is not making optimistic noises.)
(See also the comments of Judge Sinna, who criticises his colleagues for not being harsh enough on the Greeks and uses such words as "synallagmatic", "Berührungsangst" and "haptophobia".)