I think one can conclude that Judge Sotomayor is a competent judge, but not an exceptional one. She has made a couple misstatements of the law but I can't imagine that one could be grilled for three days without a few. What she hasn't done is demonstrate a particularly strong legal mind. Part of the reason may be strategic. Commentators on the left and right are fairly unanimous that she has been playing not to lose, refusing to engage the Senators and offering herself as an exemplar of a caricatured view of judicial restraint. She can't possibly believe the latter since even conservative jurists, scholars and lawyers don't think that the interpretive process is as determined as she has suggested it is.
When you go into a shell, it's hard to impress people. And she hasn't been impressive. But, at the same time, she hasn't shown herself to be unqualified or done anything that would make it tough for Democrats to support her.
As others have noted, it says something that a judge who no one really believes is restraintist feels she must pretend to be one even when the Democrats have 60 votes and the President remains popular. If, as some have said, we are all legal realists, we sure don't want to admit it.