It has been over a decade since "Monsters, Inc." and its two top scarers Mike and Sulley first proved that things that go bump in the night can be cuddly and adorable too.

Now, Pixar is returning once more to the fright factory with "Monster's University." The prequel follows the creatures from the first film during their formative years in college where they brush up on the best ways to frighten children. Billy Crystal and John Goodman return to voice Mike and Sulley, along with vocal work from the likes of Helen Mirren, Sean Hayes and Steve Buscemi.

The film opens on Friday and early reviews are positive with caveats. Critics acknowledged that the picture doesn't rank alongside the greatest works in the animation studio's canon like "Up" and "Wall-E," but said it was a charming piece of family entertainment that falls short of earlier, more innovative offerings. Many reviewers have yet to weigh in, but the picture currently holds a strong 74 percent rating on the critics aggregator Rotten Tomatoes.

Also read: 'Monsters University' Review: Wait, Didn't We See All This in 'The Internship'?

In TheWrap, Alonso Duralde said the film did have a few narrative surprises up its sleeve even as it borrowed liberally from countless other campus comedies like "Revenge of the Nerds."

"Falling as it does squarely between the studio’s classics and its decidedly lesser work, 'Monsters University' is a solidly average Pixar effort, one that brings some laughs to the kegger, but you’ll be hard-pressed to remember it at the reunion in 10 years," Duralde wrote.

Like Duralde, the Associated Press' Jake Coyle griped that "Monsters University" does not clear the high-bar raised by past Pixar classics. Yet he acknowledged that measuring Pixar against its genre-defining greatest works might be an unfair form of comparison, and seemed to feel it was better than recent, critically derided efforts like "Cars 2."

"'Monsters University’ is neither a bold return to form nor another misfire, but a charming, colorful coming-of-age tale that would be a less qualified success for all but Pixar," Coyle wrote. "The profusion of sequels is indeed dismaying for a studio that so frequently has prized originality. But ‘Monsters University’ is nevertheless pleasant, amiably animated family entertainment."

Also read: CinemaScore Gets 'A' From Studios, Especially When It Counters Critics

Yes Pixar is a business, Time Magazine's Richard Corliss noted, but at least it goes about the work of "brand extension" with more grace than other Hollywood players.

"That team now seems to be in its Post-Masterpiece Era; it’s been a long while since the astonishing one-two-three punch of 'WALL·E,' 'Up' and 'Toy Story 3,'" Corliss wrote. "But this minor film with major charms still deserves to have kids dragging their parents to the multiplex for one more peek at the monsters in the closet. With Pixar, familiarity breeds content."

Justin Chang of Variety predicted that the film would be a hit with audiences and praised the film's visual style. In fact, he liked it better than "Monsters Inc." A strong script helped the film improve on its predecessor, he argued.

"The richly rendered campus setting, whose gothic/neoclassical architecture and fanciful curriculum will remind viewers young and old of Hogwarts, is one of a few key aspects in which 'Monsters University' improves on its predecessor," Chang wrote. "Although 10 minutes longer than 'Monsters, Inc.,' the new film actually feels shorter due to a more cleverly elaborated story (scripted by Scanlon, Daniel Gerson and Robert L. Baird) that mercifully doesn’t rely on an oppressively adorable little girl for squeals and giggles."

For the most part, top critics offered an endorsement of the film albeit with reservations. Not so The Hollywood Reporter's Todd McCarthy, who branded the movie an "alarmingly lame effort" that is imagination-deficient.

"Inventiveness and a sense of creative inspiration are what set the best Pixar ventures apart, and these are the elements conspicuously lacking this time around, to the point where 'Monsters University' almost feels like a film made to fill a slot in a release schedule rather than something that simply had to be made for its own organic reasons," McCarthy wrote.

Of course, even sub-par Pixar efforts translate into box office gold, so around the corporate suites at Disney there's probably a collective sense of "eh, what do the critics know."

