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.
Why can't he be both? A villain who is driven to increasingly wicked acts by his flaws and traumas is not exactly a novel concept.
It's a question of whether his Freudian Excuse and Pet the Dog behavior are enough. There is little doubt he's a monster, but he's got sympathetic traits and is really a lot more miserable than any of his victims. That it seems to be pathological, that he didn't see what was wrong with his actions but is vaguely aware that he's the cause of his own problems, and is even more miserable thanks to that than he already was, is another pitiable point.
Also his death, being either a defiant attempt or being a total Death Seeker.
The creator's commentary also heavily implies that he has some sense of morality, continuining his destructive path because he knows he can't just turn around and render all his genocidal actions as "accidents".
Angst? What Angst?: What finally stuns Lord Shen at the end is notPo countering cannonfire with kung fu to singlehandedly destroy his fleet, but the fact that Po is neither permanently mired in a Heroic BSOD believing the lie that his parents abandoning him because they hated him, nor charging in a Roaring Rampage of Revenge for the extermination of his people.
When Po discovers what Lord Shen did to his parents, and for that matter species, his response is to...let go of his pain and find inner peace. Shen, who has never got over his own deep-rooted issues, is utterly shocked.
Played with when the Soothsayer and Shen first meet Po. They know that Shen attempted genocide against the Pandas, and assume that the reason that the Panda is here is to a) avenge his family/species, and b) destroy Shen once and for all. Both are shocked when they learn that not only had Po never heard of Lord Shen, but had no idea why he should have. The look on Shen's face when Po just brushes him off, totally ignoring the well-prepared speech upon their first meeting, is priceless.
Big Lipped Alligator Moment: Po's nightmare in the boat before the team's arrival in Gongmen. He reunites with his parents, only to find that they've replaced him with a radish which is quieter and better at kung fu than him. Said radish then proceeds to kick his ass.
Perhaps not quite as "Big Lipped," as it first appears- Po is wrestling with issues of identity, where he came from, and his origins. The fear that his parents gave him up because they were trying to replace him or that they simply didn't want him is a very real fear of some adopted people, and his mind shows this quite clearly. He wishes to know why his parents gave him up, and why they wouldn't come back for him. The radish, though, was entirely BLAM, but it was a dream. The brain uses dreams to sort out bits and pieces of information that it gathers during waking hours, and since radishes played a large role in his father's tale, it's understandable that it would make it into the dream. Kung Fu is also a massive part of his life, so it would be incorporated in as well...
Also a minor one. While trying to convince Masters Ox and Croc to escape the prison, Po delivers a Rousing Speech about how they will defeat Shen and destroy his weapon. A random prisoner then enthusiastically agrees, but he's never seen again. Oddly, he was a boar and had a completely unique character model.
Crowning Moment of Heartwarming: Tigress giving Po a hug after he tells her she couldn't possibly understand what he's feeling. Cue everybody else's shocked expressions and Crane's lower beak dropping. Later inverted with Po hugging Tigress to the same reaction of the rest.
Crane's jaw wasn't the only one that dropped. Tigress hugging Po was the biggest case of mood whiplash I've seen in a while. Literally a second ago, she was growling at Po. Viper's shout of "Tigress, no!" made me think she was about to tear Po apart. The hug was a pleasant surprise.
Anyone who saw the short on Tigress's backstory will understand why she hugged Po, as she, more than anyone else, knows what it's like to not know where you come from.
Don't forget "Po Finds The Truth"! Everything in that track from 1:00 on is absolutely chilling!
Followed by the powerful overture starting at 3:55 as Po realizes that Fate balanced the scales after his loss with a life filled with new fathers, friends and soaring achievements he never dreamed he would gain.
And let's not forget the most powerful part of that song that played during a certain tearjerking moment: Po's mother hiding baby Po in a radish crate and then drawing away the wolves and Shen.
Fridge Logic: In the final fight scene, you might wonder how the cannon was held up by ropes attached to the ship's deck - the ropes actually held up the pieces of debris supporting the cannon's base. When they broke, the wood shifted enough for it to overbalance and fall.
Foe Yay: Sure, he was talking about his cannons, but there was just something about the way Lord Shen stroked Tigress' face with the tip of his wing, whispering, "Beautiful..." that invoked this in so many creepy droves.
Boss Wolf mentioning how "Cuddly" Po is on a few ocasions.
Germans Love David Hasselhoff: For all the good reviews and the high Cinemascore audience grade of the film, the film unfairly underperformed at the box office in North America although the domestic gross it earned did more than pay for the production budget. However, internationally, especially in China, the film became the #1 animated feature film worldwide of 2011.
Moral Event Horizon: Lord Shen, as far as he appears on the screen, always was a power-hungry murderer, but he really crosses the line when he massacres an entire panda village.
As if that isn't enough he coldly kills the Wolf Boss just because the Wolf Boss didn't want to murder his own men.
Narm: Po's "IIII loooove yoooou guyyys" line during the final battle can come off more Tastes Like Diabetes than a Heartwarming Moment. Though it's arguable whether or not this line was meant to be taken seriously in the first place.
Tear Jerker: Po finally remembering how his mother was forced to hide him before she lured away Shen's forces and he never saw her again. This is hands down the saddest moment in a Dreamworks Animation film.
Master Thundering Rhino being blasted to bits by Lord Shen's cannon.
Tigress's Futile Paw Reach as Po is shot. Later, Po finding a badly injured Tigress after she took the bullet for him.