As of episode 10, there are only two episodes to come.
Unless they massively flubbed the ending its safe to say that Princess Principal is the sleeper hit of this season. Surprisingly, “Cute Girl James Bond Spy Action in Steampunk Alternate Past!London with bonus yuri-subtext,” is the anime that I didn’t know I have been missing.
The show took its cues from Haruhi and airing the episodes in anachronistic order. Since the episodes are mostly self-contained stories it is not bad plotwise. Astute viewers though who pay attention to the chronology may find themselves a bit spoiled at certain points.
Episode 1 itself is one of Princess Principal strongest cases and do a good job of establishing our protagonist so I don’t mind them using it as an opener.
In any case, let the analyzing begin. <Warning spoilers below until episode 10>