From reading the module description above, both players & DMs know pretty much what they are getting into, and it's a fun ride! There are some great role-playing moments and combat encounters are interesting -- although players mostly know what to expect. Keep in mind that this is a "funhouse" module where PCs wander from room to room and the monsters jump out. Inexperienced PCs may need some prompting to get them moving in the right direction. Faction goals were a little weak but easy enough to accomplish.

Here's my suggestion to potential DMs: develop the NPCs very strongly at the beginning. Play up the snobbish Taldan attitudes (a Paris Hilton-esque spoiled rich girl who needs a bad boy to piss off her parents, or the boys club of braggarts, scoffing generals) and develop some NPCs for sympathy (slave boy ordered by his child master to insult an ugly character, lost little girl, ostracized intellectual). Later, when these NPCs come back as zombies out for blood, watch your PCs attack with glee or regret their attacks to put the zombies down.

Mood music for your listening pleasure.

...as the PCs get, what they expect and the scenario is well-laid out.
However, I would have liked to see a more complex adaption of the "Undead Opera scenario" - i.e. as a Pathfinder module or as a part of an adventure path. Including some Phantom of the Opera references or any kind of imaginative twist.

One of the several things I enjoyed about this scenario was the directness of the blurb. It tells you what to expect so there’s no feeling of injustice when the battle royal breaks out. The setting for the scenario is really what makes it memorable. Some players may be discouraged from playing certain PCs because of their lack of culture or interest in the ‘fine arts’, but the author has made allowances such that all PCs will have their chance to shine in the course of the scenario. Play the character you want to play (but pay attention to the blurb too!).

Also, I enjoyed the glimpse into Taldan society. It helps the players who don’t devour the sourcebooks to understand what Taldor is all about and why it has fallen into decadence and complacency. Anyone who plays this scenario will forevermore carry an image of the Taldan faction in their minds.

The scenario can run very quickly also. As with Mists of Mwangi, a prepared DM may run it inside of two hours. I like to pre-draw my maps in color on giant graph paper, and the opera house is wonderfully detailed and if you take the time to give it the attention it deserves your players will sing you praises :).