1.) It has a novel motion-sensing controller
2.) Its graphical horsepower is substantially worse than the 360 or the PS3
The graphical horsepower issue is sort of a mixed blessing. On one hand, games on the Wii tend to look worse than they do on either of the other consoles. Sure, art direction can mitigate the hardware issues, but only to a limited degree.
The fact that the Wii is limited to 480p is almost a dealbreaker. Once used to 720p+, 480p is noticeably pixelated. It looks terrible in comparison.
However, on the plus side, games are cheaper to make on the Wii - you don't need extremely high-res art assets (or high poly models), your environments by necessity have to be smaller and less densely populated, and AI and such have to be much less complex. This means that compared to the 360 and PS3, game development on the Wii costs much less, and involves less risk.
The motion sensing is a similarly double-edged sword. On one hand, you have a really novel, accessible control scheme. Players can mimic real-life motions in games like Wii Sports, and feel like they instantly understand how to play the game. You also have a pointer, which by now is almost a universally understood input mechanism.
The problem is that the technology is really limited. It can fake a lot - Wii Sports is a great example of taking only the "right" data, faking a lot, and really creating the illusion that the Wii can understand subtle and complex motion inputs. There are undoubtedly ways of tricking the player into believing the hardware can "understand" more than it can, but it's not as easy as players might think.
Still, the biggest problem with the Wii's motion-sensing capabilities will likely eventually become its biggest strength: Game designers don't have a clue what to do with the Wiimote. In The Legend of Zelda: Twilight Princess, the controls are essentially a remap of the Gamecube controls with some minor "waggle" and pointing added for effect. In practice, it's functionally *worse* than the Gamecube controls.
Similarly, a game like Alien Syndrome should have a relatively simple control scheme - one stick for movement, one stick for camera control, and some buttons to shoot, change items, and the like. Problem is, the Wii has no second stick for camera control. As a result, the game completely botches the control scheme in order to get camera control *somewhere*, by putting it on the tilt control on the left-hand controller. It's insane.
But that's the crux of the problem. Some games simply *don't work* with the Wii's control scheme. The dual-analog control that has become the standard over the last few years often cannot be elegantly remapped to the Wii. And even if it could be, it shouldn't be.
The thing that people love about the Wii is the belief that you're *doing* something. Wii Sports works because people can utilize their real-world knowledge about the sports they're doing. Warioware and Zack and Wiki work because the motions of the controller mimic, in surprising ways, motions the player is already intimately familiar with.
Once people figure out how to make games that focus on the *right* way to use the Wiimote, Nintendo will have a lock on that whole genre of games. But until then, you get games like Alien Syndrome, which are really square pegs in round holes.
Even Super Mario Galaxy, hailed as one of the best games of all time, doesn't really use the Wii to its fullest. Almost everything about its control would have been better on a Gamecube pad. And with the exceptions of Wii Sports, Warioware: Smooth Moves and Zack and Wiki: The Quest for Barbaros' Treasure, that's true of all the Wii's games.
It's going to take a generation or two before designers really "get it," or for the technology to allow for better recognition of high-speed motion. Until then, the Wii remains a console with more potential than most people know what to do with.
Recommended on the Wii:
- Wii Sports (obviously) A/100
- Zack and Wiki: The Quest for Barbaros' Treasure A/(85ish - not far enough in to really give it a definitive rating)
- Warioware: Smooth Moves B/85
- Super Mario Galaxy B:/85
- Alien Syndrome D/20
- SSX Blur (an interesting, but failed attempt at a novel control scheme) B/35
- MySims (a game that strips away what makes the Sims interesting, and replaces it with painfully clumsy and boring "construction" tasks) A/15