I've been an on-and-off follower of FOP for many years since the show first premiered on Nickelodeon networks a decade ago. It was only after Abra-Catastrophe, and later, Channel Chasers, when I truly became a fan and a dedicated follower. However, like so many others, my interest wained in the years. More interesting cartoons came and went, fan's wishes were never granted (pun not intended), and the show itself got exceedingly boring, essentially becoming a caricature of itself. Yet, like the Simpsons, Family Guy, and so many other everlasting cartoons long past their due date, it manages to recapture my attention every once and a while.
I guess the best place to start at is where it all began, or rather, where it all started to go downhill. It seems many fans are conflicted, I've heard people say it should have ended at Channel Chasers, others blame Poof's birth, some even say it took as long as Wishology to start going belly up. I'm personally torn. I believe the show starting losing its comedic value the season after Channel Chasers but before Poof's birth. However, the episodes from Poof onward are absolutely terrible: they lack any real comedy, are packed full of toilet/diaper humor, and focus on lame or irrelevant characters (Dark Laser, Mama Cosma, Foop). Only the coloring work looks better, but some of the animation is still crap. The plots are all recycled from earlier, and better, episodes.
Cosmo, Crocker, Timmy's dad, Jorgan, and Poof are used in pretty much every episode, and they just aren't funny anymore, they need to be given a break. The episodes were Timmy chases after Trixie are painfully boring, predicable, and unwatchable, and that "shipping" has gone nowhere in the past 10 years. But I also hear they are making a live action movie where Tootie gets hot and Timmy wants to marry her. As much as I know not to ever put stock in a live action adaption of a cartoon made by Nick ever again (AIRBENDER), I might watch this anyway because its honestly the most interesting thing they've done with the cartoon since they announced Cosmo and Wanda were having a kid (and then promptly ruined it by making it a male pregnancy...), but there are some people who are saying the live action will ruin the cartoon. Sadly it is already way to late for that.
For people who are watching this cartoon off recommendation, stick with Season 2-4.