It's great to find someone who also played the old R&C's, really. And yeah Up Your Arsenal is awesome, but for me it can't be compared to Going Commando. UyA felt a lil bit more... Childish? I don't know how to explain it at all but yeah it's kind of that, and I'm talking about the 10 y/o me. GC felt like more serious stuff, for example it used to give me that 'butterflies in my stomach' feeling everytime I was just about to face new boss. That's something that UyA didn't get to create on me at all... Well excepting that one planet called Koros I think, which was hard as fuck. I consider the graphics were also better in GC, the scenery in general looked much fresher to me.
About the OST, it comes to the same thing. UyA sountracks were great, but GC ones were better in general to me. I'd say these are my favourites from both games, who it's hard choose just a few:
