Online multiplayer is more rewarding than the solo campaign.
If you've ever played one of the Modern Warfare or World of War games online, you've already played GoldenEye 007's online multiplayer, and that's a good thing. I've become so addicted to this online game that my wife has threatened to unplug the system. Playing GoldenEye online is more rewarding and more fun than the single-player campaign and local multiplayer games. Online, there exists progression on a large scale - a feature that's largely absent from the offline modes. If you have the means, take this puppy online. You won't regret it.
While it doesn't offer the same kind of customization that the local multiplayer games do, Bond online allows you to customize your character's loadout - an especially important task that not only offers you certain advantages (often map-dependent), but also gives some indication of your standing in the online community. When you start out, you have paltry options and you're better off using one of the pre-made loadouts. See, the key thing in Bond is that the more you play, and the better you perform, the more experience you get. When you level up enough, you have access to previously locked guns and gadgets. At level 25, you start unlocking additional gameplay modes, so the incentive is definitely there to keep improving. You can customize five different loadouts, and believe me - it's crazy fun experimenting with different gun and gadget combinations. If you find that the loadout you chose isn't cutting it, you can switch your loadout during the game!
Experience is gained many ways, but mostly from killing fools. Headshots get you more experience than straight kills, as do melee attacks. Melee attacks are particularly satisfying, especially when you come up behind a camper who thinks nobody will find him: MELEE KILL (+10 XP)! Eat it, sucka! Winning matches nets you lots of experience, as does achievements, like your first play on a given map or gameplay mode, or getting a whole lot of kills with a particular weapon.
Of course, the usual online annoyances are here, too: Sore loser hosts who quit the match when they're not winning, thus depriving you of all your hard-won experience; campers (and no kill cam to hunt them down); and of course lag. While occurrences of lag are irritating, it results in some hilarious mismatches. At one point, I snuck up behind a camper and melee'd him, but he didn't die. So I beat on him like three more times, only to realize that lag was affecting that match, he'd gotten around me, and melee'd ME! It was hilarious. And honestly, the game does a great job of matching you up with well-connected players, so lag is rarely an actual problem. There is one Wii-specific downgrade that I very much appreciate: no voice chat. If you've ever played a match of Modern Warfare 2 online, you might understand why I'm grateful for its omission.
All of the local multiplayer modes are also available online. My favorite is an old standby: Conflict (Deathmatch), the classic free-for-all which, given the right map, I can completely dominate (play me in the Sewers…I dare you).
The online game is insanely fun, and I can't recommend it much higher. If you have Goldeneye 007, a Wii, and a Wi-Fi connection, you need to start playing this.