When Undying's focus is on the narrative, it's an interesting, atmospheric and a really unique game. However, once it turns its attention to combat, it quickly becomes a tedious snoozefest. It never really manages to intertwine these two aspects effectively, nor does it balance them in a good fashion.
Pros: Well written journal, interesting story, good music, moments when you look at the alternative reality are usually cool, at times it's rather atmospheric (mostly at the beginning), some cool spells to use, some neat ideas and moments
Cons: Average shooting and it relies heavily on it later on, once you get some of the spells (and one weapon in particular) the game becomes a cakewalk and loses all tension, half of the weapons and spells are mostly useless, clumsy management of weapons/spells/inventory, alternative reality moments are sparse (especially later on), cutscenes verge on being a parody, NPC's (lack of) reaction to the events is immersion breaking