Yeah, it is. There are way more facial features for mii's. Plus, you can just take a snapshot of yourself and your mii will have your face. (or atleast a face that is similar to yours). It seems like Mii's have a much bigger role on the 3DS, considering that you need one in order to play Streetpass Mii Plaza, where you get to be a king/queen that gets kidnapped and you need the help of other heroes(people that you have a streetpassed with, or a hired dog/cat/bunny mii that you can get by spending play coins you earn.) Also, in nintendogs + Cats, it appears that you're playing as your mii, and you get to meet other miis who have their dogs out.