Getting stuck all the time....aarghhh!!!

What do you mean by "Crashes and stuck"? I played the entire game without one crash or being stuck at all (on 360). UPlay is very buggy/glitchy BUT you don't need to be signed in. So don't be alarmed when UPlay never connects. From my experiences though you still get all of the achievements and stuff via UPlay. You do NOT have to retain internet connection though...at least not when I was playing. Hmmm...what else. If it's disc read error, then clean the system/disc. If the game itself is freezing then it's either an issue with the 360 (I doubt it if other games work) OR it's a faulty disc. I would try their first before worrying about your system. What exactly is it glitching on, where is it hanging/freezing. How is it hanging? Does it just freeze up...when it freezes can you still use the X-Box controller center button to bring up the entire menu, or does it freeze up the entire 360? Specify some of this and we might be able to troubleshoot you a solution.