The 2DS originally launched in red and blue models (called Blue + Black and Red + Black in press materials) to start and will be sold alongside the standard 3DS (still available for $169.99) and 3DS XL ($199.99) in the US.
The 2DS is fully compatible with all 3DS and DS games but does not include the ability to display games in 3D. It still features all the functionality of 3DS (WiFi, local multiplayer, etc.) and can be put to sleep using a slider that replicates closing the clamshell on a standard 3DS. WiFi can still be turned off, though it’s done via controls in the software rather than with a physical switch.
It's important to reinforce that the 2DS is Nintendo's no-frills, entry-level portable. The 2DS plays nearly all games for the Nintendo 3DS platform, but it can't display anything in 3D. It also has the smallest screens of any of the current DS models, and it doesn't have a great-sounding speaker.