Ok, this game is pretty much identical to the Dreamcast version in terms of levels and songs from what I remember.
For those not in the know:
You need 2 Wii remotes. You have to shake them to a beat of a song in the positions indicated on the screen - 6 possible positions for a Wii remote.
Think of the Guitar Hero or Dancing Mat games but with Maracas.
Then there are "Poses" where you hold the remotes in the indicated position. Then "Dances" where you move the remote(s) over the indicated spots. (A moving pose effectively)
You do not need to calibrate your Wii remotes, it says "player calibration" as far as I can figure you are calibrating yourself.
Samba on the Dreamcast meant you had to choose your height, then move the maracas up and down to hit those spots. The Wii version has you pointing up, forward or down. Does this work? I think it does, I find myself almost naturally doing this as I raise / lower the remotes anyway.
A few odd things when you shake them, it seems you can almost "blag" some points by vigorously shaking the remotes to cover 2 spots, as opposed to just the one. This does not mean you are going to complete the song this way. I also found dance moves can be done by shaking the remotes vigorously with more reliable outcomes then trying to do it properly.
It feels sometimes if you shake the remote too quickly before you move it into the correct position, it won't register that you are in fact shaking it in the correct position. I guess it is limitations of the remote. So occasionally it gets annoying.
On difficulty, I was able to get through Easy and Normal levels on my first attempts, with A ranks. Hard need a couple of attempts. I did these first 3 in one evening. Super Hard needs more attempts - not completed yet. It gets to the point on Hard and Super Hard where you can think "AHH, what is going ON?!?"
The songs - well - I have to say compared to some of the other games, I like the songs, I think they got a good selection. The should be more pleasing for most people. Soul Bossa Nova, Dance mix of Tubthumping, Rock version of Take on Me (Reel Big Fish I think), Sway, Smooth, Low Rider to give an idea.
People will laugh at you for buying it, until they get into it, it can be a great game to play with your friends, as you compete to do better.
The are some mini games, like whack a mole, or brick breaking.
There are some multilayer games, like Co-operative or 1 vs 1.
You can buy songs as well, the first pack had 3 songs for 500 Wii Points (about £5) if you feel it is worth it. Personally I would rather 5 songs for 500 Wii points at least.
Turn the music up to get yourself into the song and really do well!