Bought a 3DS the other day. So far I am liking it. Its weird having to continually use a stylus with Epic Mickey just to erase or create platforms, canons, and people. Didn't have to use the stylus too much with Castlevania Mirrors of Fate.
I never use the stylus except to navigate the eShop menus. You can use your fingers during games that's what 99% of the people who have a 3DS use.
Don't worry about what a few people say about using your fingers on the screen, they really don't know what they are talking about. People have used their fingers on DS/3DS screens for years and it doesn't do any damage, just clean it with a cloth once in a while and you're good to go. Games would be a pain in the ass to play if you had to use a stylus the whole time. There are a select few games where it helps to be as accurate as possible, but for the most part just use your fingers (if you want to anyways, if you like the stylus then forget this post lol).