I've already posted on this topic, but for it to be a success, it needs to have:
An exceptionally fun bundled game akin to Wii Sports or some sort of shooter compilation.
It must come packed with a set of drivers to enable existing top-shelf games to use the new remote instead of the dual analog. Note that means a nunchuck type attachment is probably a must. Imagine buying it day one and getting a cool pack-in PLUS drivers for the Halo Trilogy, Bioshock, Mass Effect, and a couple of upcoming titles. The more the merrier here...
They need to throw some money at all of the major developers that have a game in the pipe to develop a control scheme supporting the new device. Ideally it would launch with the game but adding it shortly after as a patch would be fine, too.
Microsoft needs to put together a "best practices" for the device along with an SDK to enable developers to use pre-provided engines to handle the remote. If it is implemented like crap, it will fail miserably. Microsoft's trend seems to be to release something "good" and make it "better" with a service pack or other upgrade. They can't play that game here. It has to shine -- no, blow people away -- right out of the box.
If they manage to pull of the above and sell it for no more than the cost of a top-shelf game -- $59.95 -- they'll be fine and sell boatloads. Otherwise it will be a failed 3rd party device. Microsoft won't go this far, however, as this isn't the way they do business. It'll more than likely be a half-assed attempt and will fail. The above approach will not make them money. It will cost them in the short-run and they aren't any more interested in taking more losses than Sony is so I don't expect them to do it right.
On that note, assuming the above was what MS was really planning to do, I'd get one in a heartbeat as I'd have lots to play (and re-play) and would feel my money was WELL justified. Sadly, I expect they will pull a scene-it. One third party controller and game and nothing else to use it. Fail on an EPIC scale.
I hate trolls.

Systems I currently own: 360, PS3, Wii, DS Lite (2)
Systems I've owned: PS2, PS1, Dreamcast, Saturn, 3DO, Genesis, Gamecube, N64, SNES, NES, GBA, GB, C64, Amiga, Atari 2600 and 5200, Sega Game Gear, Vectrex, Intellivision, Pong. Yes, Pong.