Based on the reviews, I think Metroid Prime 3 has a big potential to capture Halo fans who have never heard of MP3. The only thing lacking for this game is online play.

My Prediction: Let's say 20% of Halo 3 buyers might consider MP3, that should be a good extra 1-2 million sales for MP3 for a world total of between 4 to 6 million. Just about 2-3 million shy of MS's biggest game Halo 3's world total.

It is important. If marketed well Xbox/PS FPS fan might consider it and even buy it.

My thoughts is that any speculation of Metroid needing to be a Halo-killer is ridiculous. In regards to sales, it will never approach the mass-market appeal of Halo. Halo is a mainstream, across-the-board, success(in other words, well beyond simple hardcore appeal, like Mario, Final Fantasy, GT, etc). Metroid has never spread too far beyond the hardcore crowd, and it may never. Speaking soley for myself, Metroid could never be a Halo-killer, because Halo never toppled Metroid in the first place.

Metroid is important as it could get PC gamers into buying the Wii for it's FPS's, IF Metroid's controls are spot on.