I Have thought a lot about a reply since you first asked for a review. I Have listened to Servilia around eight times and I am getting to know it very well. There are wonderful melodies and brilliant orchestral effects and unusually for Rimsky some passion. I haven't a clue about the plot or whether it works well as an opera, I like it very much.
This is good to know, thanks Hatoff. I can fill in on the plot. Somewhat unusually for Russian opera it's set in classical times* - the story is set in Ancient Rome during Nero's reign.
From wikipedia -
Servilia, daughter of the senator Soranus, is desired by her father to contract an alliance with Trasea, but the latter, hearing of her preference for his adopted son Valerius, withdraws his suit. Egnatius, the freedman of Soranus, being enamoured of Servilia, conspires against his master and Trasea, and intimates to Servilia that her submission alone will secure their safety. Valerius has mysteriously disappeared, and Servilia, becoming a convert to Christianity, renounces the World. Called before the tribunal, Trasea and Soranus are sentenced to banishment, while Servilia is awarded to Egnatius. Valerius now returns, bearing a proclamation from Nero that the tribunal is dissolved. The sudden reappearance of her lover causes Servilia's death, and Valerius is only prevented from destroying himself by the intervention of his foster-father. Egnatius, in his woe, invokes the Divine Being, and the rest join him in acclaiming the Christian God.* - I can think of only a few Russian (recorded) operas set in classical/ancient/Biblical times: Mussorgsky's Salammbo; Serov's Judith....the majority of Russian opera is based on more recent European literature, (Russian) history and also of course Russian fairytales and myth. Fair comment?