The way I see it is that Rare suffered a 'brain drain' in the years preceding and when they transfered to Microsoft. Pretty much the entire team that made Goldeneye, Perfect Dark and Blast Corps went their own way and formed Free Radical. Nintendo, of course, syphoned off a lot of Rare's talented individuals into their 1st and 2nd parties such as Rare and Silicon Knights.
IMO, the last game made by Rare that wasn't to me disappointing was Star Fox Adventures (and that was probably because at the time I hadn't played any other starfox games)








