I just racked my first ever brew from primary (bucket) to secondary, glass carboy. I am seeing after the first few hours that the top portion of the brew is starting to clear as yeast falls to the bottom. I am thinking that one potential benefit could be a clearer/cleaner final product? Also, I would think that an extended secondary fermentation would allow flavors to blend and mellow over time. I am no expert in brewing, but am well versed in the world of cooking and there are many similarities.
I have done a ton of research, and my research indicates that a secondary is not a necessaty to make good homebrew. I consider it just another way to improve your brew....also gives you another opportunity to impart flavors ie..dry hopping, spicing..etc..etc..
but what do I know, I am just starting out!