Hit. No doubt.

at 20 a pop how can it not be a hit?

Hit. It however better be a completely game in comparison to Wii Fit because in its own right, it pretty much is an expansion, and $50 for a game that you already played with a few minor tweaks isn't worth it. Still, its a Hit if its vastly improved from the previous game.

Its $20!? (Obviously, for the game alone) Then its definitely a hit.

I would really like a website for confirmation.

@SuperiorX: If this qualifies as a source:
http://wiifit.com/

[WII] Wii Fit Plus (Nintendo) - SA 108,000 (42%) / BB 9,300 (16%)

first day in Japan.

Seems rather low for 3,5M wii fits in Japan and might be below Wii Fit first week.

The first day numbers are still pretty good, though.

http://www.amazon.com/Wii-Fit-Plus-Nintendo/dp/B002BS47JE/ref=sr_1_1?ie=UTF8&s=videogames&qid=1254524698&sr=8-1

$20 for game only

$100 w/ balance board

First day numbers are decent.

Will need to wait a few weeks to see if Wii Fit owners are upgrading or not.

Considering it's more of a continuation of Wii Fit rather than a whole new piece of software, I would expect sales of one to transfer seamlessly into the other.