Well, Microsoft attempts to compensate by giving players some features you usually associate with subscription services like, uhh... Okay, I dunno, but there are scoreboards n stuff.
In the end I guess you pay 50 bucks to hook into a pretty standardized service. You know there's voice chat, everyone playing (okay, 70% now thanks to 2 months free) have a mic, and so forth.
Having that said, xbox live was the worst 50 bucks I've ever spent. People have told me it depends on the game, but I've experienced nothing but an inane amount of bitching. Nothing says quality quite like a 7 year old black kid talking smack about my dear momma. Yes, the fact he was black made it funnier.