DreamWorks Animation SKG (NYSE: DWA) isn't getting the returns it's used to on investing in a fourth Shrek movie. But it's way too early to call the movie a flop.

Shrek Forever After opened this weekend with a chart-topping $71 million debut, easily kicking Iron Man 2 to the second-place scrap heap but falling far short of the record-setting attendance for Shrek 2 and Shrek 3. That's despite higher ticket prices in a nationwide 3-D rollout with a healthy jolt of IMAX (Nasdaq: IMAX) sales to boot, which added $15 million to the box office total altogether.

The 3-D and IMAX boosts won't last long this time, unlike fellow DreamWorks fantasy How to Train Your Dragon, which ruled the multidimensional theater space for a long time. Walt Disney (NYSE: DIS) brings the eminently bankable Toy Story franchise into the third dimension when Toy Story 3 debuts on June 18, likely stealing a fat slice of Shrek's target demographic.

But all is not lost for Stock Advisor pick DreamWorks. For starters, a $71 million debut may be disappointing when compared with the other Shrek titles, but it's still very impressive for an animated feature -- rated PG, no less, which means losing a great big handful of matinee-priced tickets. But most importantly, the real litmus test comes next weekend.

Hollywood.com analyst Paul Dergarabedian expects the movie to "have legs throughout the summer," with or without inflated 3-D ticket prices. And I would agree. Word of mouth is a powerful marketing force. Gigli and the 2009 remake of Nightmare on Elm Street disappeared almost completely in their second weeks, because the brave souls who saw them the first week wouldn't recommend them to friends and family. But it's not unheard of to have follow-on weeks staying strong or even rising above the debut, as the original Shrek did so long ago.

I've seen Shrek Forever After and would certainly recommend it to others. It's not a happy-go-lucky cavalcade of cheap jokes like some of its ancestors, but a well-designed (if somewhat formulaic) story with a tearjerker hook without losing kiddie appeal. Critics have not been overly kind, but I can see the mass appeal here. I'm not saying that this movie will accelerate its box office take, but the decline should be small enough to give Shrek those sexy summer legs.

Shrek's endgame is out of DreamWorks' hands now, and distributor Paramount (a Viacom (NYSE: VIA) company) can't help either. It's up to John and Susie Q. Public to complete the picture, and I think the ogre will end up looking pretty good.

Fool contributor Anders Bylund owns shares in Disney, but he holds no other position in any of the companies discussed here. Walt Disney is a Motley Fool Inside Value pick. IMAX is a Motley Fool Rule Breakers selection. Walt Disney and DreamWorks Animation SKG are Motley Fool Stock Advisor recommendations. Try any of our Foolish newsletters today, free for 30 days. You can check out Anders' holdings and a concise bio if you like, and The Motley Fool is investors writing for investors.