The DSi is great too of course, but if the scaling of DS games is a problem for you on a 3DS you can display the games unscaled/letterboxed by launching the gam

The DSi is great too of course, but if the scaling of DS games is a problem for you on a 3DS you can display the games unscaled/letterboxed by launching the game (or TwilightMenu) while holding Select or Start. I too much prefer displaying them without the bar scaling. The same trick works for Virtual Console games including GBA titles.