If I were rating this, I'd deduct 4 stars for the Flappy Bird alone..
Burning hatred for all things Flappy aside, after playing through I'd give this a solid 4.
It comes up short for me in two areas: one, though it does a decent enough job explaining who the characters are in-game, I still sort of feel it leans too heavily on PW lore, and you had to have played the games to be able to fully enjoy it. Not really much the dev can do about that, its just the nature of the parody beast.
The other is I feel it would have been better if Maya's corruption would have been tied to Phoenix's actions rather than hard-scripted. What I mean by this is have it tied to Phoenix "wasting time", ie. asking people unnecessary questions, unnecessarily examining things, using the x-ray when not necessary, getting his dick wet, etc. Every time the player does something other than the absolute bare minimum required to advance the case (even if it means missing out on "flavor"), Maya's corruption advances a point. Something to consider for any future games of this format.