I recently took it upon myself to watch every, single episode over the course of a few weeks.
I found the characters to be much more interesting, dynamic and likeable watching it all in such a short space of time because all of their many adventures and quirks remained fresh in my mind. Over the course of, say, 16 years, much of it gets forgotten. This way, you can really appreciate the characters as the sum whole of their parts.
On the downside, now my mind seems to be permanently trapped in Elwood City. I can't stop watching or thinking about it. Almost ritually, I re-watch at least 3 episodes a day.
At least it'll be Pony Day soon.