Yesterday, Microsoft announced launch of Xbox Originals, which allows Xbox 360 players to download and own full Xbox games, but today it turned out that it is not that great after all.
Turns out, those Xbox games have not been imported to Xbox 360, instead they will be emulated and it looks that they suffer from emulator-backward compatibility bugs. Microsoft has set up an Xbox Originals - Known Issues web page to which lists known bugs which range from "some minor flickering at the top of the screen that happens very rarely" in Crimson Skies, to HDMI 720p not working at all for Psychonauts PAL players.
Major Nelson also confirmed that Xbox Originals won't have additional functionality like Achievements and Gamer score. The answer is no. "These are the original games that were created before Xbox 360. In order to preserve the integrity of the original gaming experience they provide, they will have the features available at the time of their initial release."