I have both the DS and the Wii Versions. Both are excellent. The Wii version is getting a lot more play time in my house due (1) it's our newest game and (2) the multiplayer. My wife and I go head to head in the mind sprint and every game comes down to the wire. It's great casual fun that can actually help keep your brain fresh. I would highly recommend it.
I have the Wii version and I love it. My friend and I compete all the time, if you get it and you are competing with each other, you'll find that you can't stop until you beat that other person's score (unless you are not competitive). I ended up paying $67 CDN for it at Walmart (yeah that's sad), but I don't mind (yes i do, i'm still crying cuz it was so much), but I rather buy it legit than to modify my Wii and buy illegal games (Damn it, why can't they make games cheaper grrr).