The fourth season of “Glee,” which ends Thursday with the “All or Nothing” episode, has elicited the epitome of a mixed reaction from fans and critics.

On the one hand, strong cast performances and a handful of compelling storylines and character moments have helped the show emerge from its third-season abyss.  No critic argues “Glee” has returned to its inaugural season heyday, but when compared to the low-points of the show’s third season, the current year has provided a welcome improvement.

On the other hand, storyline and tonal inconsistencies continue to plague the show.  The musical performances, once the clear highlight of “Glee,” have become less imaginative and more hastily-produced.  And, thanks to the introduction of several new high school characters, “Glee” has diverted attention away from many of the original and veteran cast members who helped cement the show’s fan following.

But insofar as “Glee” usually does big moments well–even the third season wrapped up beautifully–viewers definitely have optimism ahead of the fourth season finale.  While early renewal for seasons five and six assures cliffhangers are a possibility, Thursday’s finale will certainly make progress on key storylines, including the New Directions’ latest regional competition (with “American Idol” runner-up Jessica Sanchez guesting as a rival competitor), Rachel’s final audition for “Funny Girl,” Brittany’s interest in MIT and Ryder’s interaction with a “Catfish.”  Kurt and Blaine–“Klaine,” as fans call it–will meanwhile consider the future of their relationship.

Photos from “Glee” season finale “All or Nothing” follow: