a lot of those are MS/Xbox exclusive properties anyway. For the likes of Halo, you might as well just go "Oh hey wow look at FFXIII EXCLUSIVE TO PS3", or the same for Mario/Zelda and the Wii.
However, the likes of Splinter Cell 5 and the exclusive chapters for GTA4 are definitely damn good aquisitions, and the kind of titles that make me (finally) want a 360. The potential of a new Banjo-Kazooie unrestricted by the N64's blur and framerate issues has me excited too. The original was better than Mario 64 imo, so here's hoping they do the sequel justice.