I didn't see it in the stickies so here goes.
Sora, Tiagra, 105 and so on, are the differences in price noticeable compared to the benefit of the increase of......goodness?
What is the point of diminishing returns dollar wise? Is Sora bad? Does it have to do with the shifters? Hows about the the derailleurs and cassettes? Chains?

I'm just getting back into cycling so please be gentile with my ignorence.

Thanks as always,
Ray