Unlike most superhero movies, Fantastic Four doesn't go down the predictable route of a megalomaniac villain seeking world domination / destruction - rather Doom spends most of the movie brooding over the accident and his unrequited love for Sue. Meanwhile, our heroes just sort of sit around, not doing much particularly superheroic at all. Johnny uses his powers for fame, The Thing has a hard time coming to terms with his deformity (and his rather outdated prosthetic suit), whilst Reed and Sue engage in a few will-they-won't-they scenes.
While the storyline isn't predictable, this is more due its being threadbare rather than being unpredictable. Virtually nothing coherent happens throughout the movie – the group have their accident, play around with their powers in not particularly useful ways, then eventually have a single brief scrap with the ill-conceived camp villain at the end.
The acting is variable. Chiklis is impressive and has quite a screen presence (owing partly to the character's size), whilst Evans is charming and entertaining. Alba is fairly unnoteworthy apart from the cynical use of her cleavage and Ioan Gruffudd is remarkably uncharismatic and forgettable as the team's leader.
The action scenes are decent though not excellent when they appear, however there are really only a handful of bona fide action sequences throughout. Considering this movie is supposed to be fun rather than being deep and meaningful or having a particularly brilliant plot, it would be tempting to say "just sit back and enjoy the action." However, this is made slightly problematic since the movie is hardly action-packed.
Fantastic Four does not expect to be taken seriously, making no attempt to achieve the semi-realism of the recent Batman Begins. In terms of dialogue, there are bucket-loads of the cheesy, corny lines you'd expect from this kind of film, a fine example being the cringeworthy uttering of Invisible Woman to an the amorous Mr. Fantastic: "That's my nose, silly. These are my lips."
Fantastic Four is not a good film in terms of having a decent plot, or any plot for that matter. The acting is hardly going to win anyone an Oscar, nor is anything else. On the bright side, it has its funny moments and is disposable lightweight fun for 110 minutes…and it's better than Elektra.