They still have some of these older generation games digitally available but so far the 3DS has a distinct lack of Game Boy Advance games. (invisioncommunity.co.uk)
It's nothing like the screens you're used to: it's more like an ancient Game Boy Color than the phone in your pocket. (cnet.com)
When playing an original Game Boy game on a later system, you can choose a color palette. (8-bitcentral.com)