These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Awesome Moments: Fiona gets an off-screen moment of awesome: it's revealed that after waiting so long for a prince to come, she eventually just rescued herself. And then she led a rebellion
Awesome Music: * The Piper's "Shake Your Groove Thing" sequence in Shrek Forever After. Whatever your opinion of this movie, the Ogres, Shrek, and Fiona dancing to that is awesome.
Badass Decay: Subverted with AU!Puss In Boots. He starts as lazy, fat housecat, but regains his badassery when the time is right.
Contested Sequel: Shrek Forever After. To some, it's a mild improvement on Shrek The Third but still not a very good movie. To others, it's a huge improvement with an interesting plot, tons of Continuity Porn and a great villain, and indicative of DreamWorks Animation's beard-growing. While to others its worse than Shrek The Third, completley abandoning the actual characters and a waste of time.
The tagline of Shrek 4 was "THE WAIT IS OGRE!" As a result, mentioning Shrek on /co/ will often result in a Hurricane of Ogre Puns. The most notable example is this fanart getting captioned with "I'm sorry Shadow... but my time here is ogre."
Moral Event Horizon: Seen in the flashback in the alternate-universe when Rumpelstiltskin is shown completing the deal with Fiona's parents to make "their problems go away", doing so by making them go away. That would have also happened if the messenger had arrived a few seconds later at the beginning of the movie, but we don't know that at the time. When we see the king and queen's looks of indescribable horror as they realize they're being erased from existence, Rumpelstiltskin crosses the line from just a simple trickster who wanted to rule the kingdom into utterly, irredeemably evil.
Nightmare Fuel: Watching the king and queen dissolve into nonexistence is unsettling.
Or Rumplestiltkin's falling into an eternal void...
Sequelitis: Fans are divided between whether Forever After is just as bad as Third or better. Reception has been much warmer for Forever After than for Third, however.
They Wasted a Perfectly Good Plot: A charge thrown by some at the fourth film, which presents a Bad Future wherein Shrek was never born and never met his true love Fiona. It would have been interesting if someone else was Fiona's true love and seeing Shrek deal with that, but Fiona loves Shrek regardless.
Tough Act to Follow: Zigzagged with Shrek Forever After. As it came on the heels of the poorly-received Shrek the Third, it wasn't hard for it to improve on its predecessor. However, it also only came a few months after How to Train Your Dragon, DreamWorks' best-reviewed movie to date, and also had the first two Shrek movies to live up to.
What Do You Mean, It's for Kids?: The film gets pretty dark sometimes, people. From the malicious Rumpelstiltskin who erased Fiona's parents from existence and murders people (even his own followers) for his own amusement, to the Crapsack World that AU!Far Far Away becomes, there are some dark themes explored in this film.