It's very, very rare for a district court to grant a preliminary injunction in a patent case. So this case is unusual on this basis alone. Samsung will be able to appeal to the Court of Appeals for the Federal Circuit. District court judges are often reversed on appeal for incorrect claim construction, which is the definition given to disputed terms in a patent claim. Many district court judges joke that they might as well flip a coin in deciding claim construction. To avoid a preliminary injunction, an accused infringer need only raise a substantial question that the patent claims are invalid. The burden of proof is much lower regarding invalidity than it would be when the case actually goes to trial.
For those of you who have opinions about the merits (for or against) of Apple's claim, I doubt you have ever prepared a claim chart that correlates each patent claim with features in the accused product (to show infringement) or with features in the prior art (to show invalidity). It's a very rigorous analysis, which is another reason that injunctions are rarely granted in patent cases before the parties have actually completed some discovery on the issues.
This case has just begun.
So on the basis that the injunction was granted, one must assume that Apple's claim has merit enough to proceed before discovery and trial.
It means that one district court judge who has been on the federal bench for two years felt that Apple was entitled to a very rare preliminary injunction in a utility patent case. Before getting too comfortable in your assumption, let's see how the Federal Circuit views the merits. Judge Koh may grant a stay of the injunction pending appeal or the Federal Circuit could do the same.