This game may be your only chance to see Mr. Fantastic say "Main screen, turn on!"
Perhaps the nicest and meanest thing I can say about Fantastic Four for Game Boy Advance is that it closely approximates the film it's based on. If you have such tolerance for mediocrity as to be a fan of the movie, then the game should fit right in with your tastes, as it's a thoroughly competent and predictable adaptation.
The GBA version takes the form of an isometric action game with tons of combat and quite a lot of story text. Most of the levels are strictly linear – to the point that you can simply run past enemies to reach the end. You can find secret rooms with power-up items, but there are no alternate paths except in the last level, in which your goal is to find certain items rather than simply get to the end. Of course, many GBA action games are quite linear, so I wouldn't hold it against this game except that the isometric perspective lends itself so well to exploration.
Most of the game involves beating up repetitive thugs who look like miniature versions of that level's boss villain. You always control two members of the Fantastic Four at a time, except during boss fights in which you have all four at your disposal. You can freely switch among the present team members, but there's little reason to do so except to activate scripted events that require specific character abilities. In combat, the characters look different but are effectively identical for the most part. The main distinction is that The Human Torch and Invisible Woman have projectile attacks, while Mr. Fantastic and The Thing do not. The obvious differences are ignored, however. For instance, The Human Torch is always flying, but this trait only comes into play in one puzzle at the very end of the game. The Thing's punches cause no more damage to enemies than do Invisible Woman's. That's a bit silly, if you ask me.
Luckily, each character has a set of cosmic powers that add more individuality. The cosmic powers use up a special meter that is refilled by item pickups left by dead enemies. The refills are abundant enough that you can use cosmic powers almost all the time, which makes combat a good deal more fun and less annoying than if you were to use normal attacks. The cosmic powers receive upgrades in strength and range at set points during the game, which helps keep them fresh and helps you keep pace with the increasingly powerful enemies.
Most of the game's difficulty comes from enemies that crowd around you or fire projectile attacks before you have a chance to block or dodge. The levels tend to be repetitive, but very long, with regular breaks to auto save (a very nice feature) and switch over to the other half of the team. The aforementioned boss battles devolve into button-mashing; the only teamwork comes from the boss being distracted by other characters' projectiles while you attack. The allies’ A.I. is at least smart enough to stay back and use projectiles when possible.
Most GBA games aren't very long, but Fantastic Four is unusual in that it has no multiplayer mode (co-op would have worked well), no unlockables, and no reason whatsoever to play again except to relive the exact same (mediocre) adventure. The game takes about two to five hours to beat, depending on whether you run past enemies or stick around to fight just for kicks (pun intended), and after that it's kaput.
In summary, Fantastic Four is completely average and exactly what you'd expect from a licensed GBA game. There's very little bang for your buck, so it's hard to recommend a purchase unless you're such a nut for the movie that you'll play the game over and over just to see the story played out again and again. And if that's the case, why not just wait for the DVD?