The basic problem is the same as in the US: a patent-only court which is captured, or at least intellectually swayed, by those with an interest in lowering the standard of patentability. This is worse, because the Federal Circuit can never ultimately escape the jurisdiction of the Supreme Court should it choose to act. But the European Patent Court is a separate international institution, so if it is given sole jurisdiction over the European Unitary Patent, then there will be little to check it.
Where's the evidence that the Federal Circuit is intellectually swayed by those with an interest in lowering the standard of patentability? The Fed Circuit is the largest collection of judges in the U.S. that actually understands patent law (not to say that all of them do...); I wouldn't be so quick to dismiss their jurisprudence as "capture."
