In regards to gameplay, The 3rd Birthday has few errors. The shooter mechanics work, the RPG elements do their thing and it's fun, and the OverDive System also has a number of useful features. Some boss fights can be very frustrating, but the main point of criticism towards The 3rd Birthday has mainly to do with the story and characters. The story is told with many uncertainties and a very questionable ending, and the game has to deal with some terrible dialogue that even a number of famous actors and actresses weren't able to save.
The worst part is the hero herself. Aya Brea is different this time around. So don't expect the strong, interesting police officer from Parasite Eve 1 and 2. Her memory loss has her reduced to a pathetic, depressed sex object and at times she behaves like a little child. Moreover, she looks absolutely nothing like a 38-year old woman and for some reason has clothing that breaks down when she takes damage, despite not creating any noticeable advantage to the gameplay. It's just pointless eye candy.
It's a shame, because this ruins the experience for most of the game, despite there being very little wrong with the gameplay itself.