Short word of advice to anyone who buys this game who has ever played the full speed 60hz version and also owns a Gamecube - avoid this & don't bother.
Seriously, forget this and get Sonic Mega Collection 'PAL'E' Gamecube version, the GC version includes a 50/60hz option which allows the gameplay and music run as Sonic Team originally intended in Japan... full speed@60hz.
Back to the Xbox 'Plus' package - this game plays exactly like the original PAL'E' European Version - emulated 100% faithful - unfortunately its right down to the sucky 50hz style game speed and slurred music - not good.
The only plus points to this game are the range of unlockables, the fact that it is X360 backwards compatible (HD progressive scan ok - but is still S L O W).
Ok, look, the games still play 'well', but like original the PAL'E' release, its still @50hz speed... and it feels S L O W.
Options for full speed should have been introduced, no excuses.
Hear that the euro Wii Genesis/MD/SMS/SNES VC releases are also 100% PAL 'faithful' ie. 50hz speed.
IMO PAL 50hz = not welcome on any console.