Up until the end of today right? I already got it on my 3DS when it was also available at some point last year for free, as I didn't own the GBA version. It's definitely worth the price of absolutely nothing. XD I had some fun with it though, it's just really short is all. I guess that's why they're giving it away for free.
I have, and to be honest, it's not even that good in single player just because you'll have to constantly carry the second player around, and it's just a pain to do that. It is fun in multiplayer though, it's really just like Zelda dungeons and areas with puzzles to solve all revolving around the multiplayer. (hence why it's way better with more than 1 person)