This mod is not your typical four-encounters-with-some-RP-in-the-middle PFS scenario, and it has an intriguing storyline that is atypical of most PFS mods.
That being said, Midnight Mauler might try a little too hard to buck PFS trends, in turn, making for a rather unsatisfying scenario. Scenarios need to have a little something for every character, but this one leaves many characters helpless with an endless barrage of social and/or physical skill checks. While skill-based scenes within a mod can certainly be enjoyable (see We Be Goblins!), Midnight Mauler can leave an entire party feeling unsatisfied. If checks are not done within a specific timeframe, the entire party fails and takes a permanent negative to their character. The DCs are static across the tiers, leaving players in the 1-2 tier at a horrible disadvantage. I personally do not see how the average tier 1-2 party could successfully make it through this module. These skill checks do not encourage players to act as a party, and they almost seem to punish lower level parties and parties with average to low charisma. One or two low rolls at the end of the game, and you've lost.
The faction missions also contain high DCs and no time within the story to actually complete them. In fact, you are dissuaded from doing them, which makes you wonder what the point of factions and faction missions are in the first place. PCs must make a choice between faction missions and the main storyline. And even when they choose to forgo PA, there's a very good possibility that they will still fail the entire mission.
There is a space between challenging and impossible; unfortunately, this mod leans towards the latter.