However, I was rather surprised to later learn that they were able to take "Gladiator...IN SPACE!" and make it into an actually well-received story. In fact, it was one of the better stories to come out involving the Hulk in quite some time.
So when they decided to make an animated movie out of the storyline, I thought it might be worth watching. Someday. At some point.
That was 2010.
I'm...a bit behind.
So let's start with the story.
The Hulk, having smashed and jumped his way across the country (and the world, really), is captured in a way that is not explained, put on a rocket that isn't explained, and blasted off into space for reasons that are almost explained. However, they also don't explain why the Hulk wakes up as the Hulk on the ship and not as Bruce Banner. You'd think that'd be important.
The plan is to launch the Hulk to a planet full of flowers, meadows, and no sentient living things, because there he can finally be "left alone." However, the Hulk doesn't take well to being told what to do (even if it's just "don't smash the spaceship you're in and go away") and winds up smashing the spaceship. It veers off course and gets sucked through a wormhole, leaving the Hulk to crash land on a strange alien world ruled by the Red King. He's captured, turned into a slave, and forced to fight in gladiatorial games along with other slaves.
For the most part, this is an interesting mix of characters. You have the wussy coward (the bug guy), you have the sleek fighter, you have the rock guy who once fought Thor (and even does so in a flashback in the series), and you have the hot red chick who...well, she really doesn't do much of anything besides get caught, escapes with some rebels, and gets caught again. That's her entire story arc.
Hulk fights ever-increasing threats in the ring including a giant mechanical monstrosity and Beta Ray Bill (in the comics it's the Silver Surfer, but I never accepted "strong guy beats someone who can annihilate star ships halfway across a galaxy by thinking about it really hard") before winning his freedom...only to have the ruler (the "Red King") force them into a no-win choice.
Hulk and his friends escape, Hulk decides he wants to be left alone again, except when the Red King unleashes a threat that will kill all of his friends, he's forced to come back and fight it and then try to overthrow the ruler.
Spoiler alert: Hulk smashes everything he fights.
For a lengthy story shortened down to a manageable movie length, it's not bad. Characterization of a few people is lacking (see: hot red girl), and the movie does assume that if you're seeing something called Planet Hulk then you have more than a passing knowledge of who the Hulk is. I can't really fault them for that.
As I said before, it's hard to get excited when a story line is "will the Hulk smash things." It's like asking if a bus tour of Nebraska is going to involve "roads." Does it hold up as a Hulk story? For the most part, yes, but if you want to avoid spoilers, don't read the next section.
The thing about comic books is that, eventually, they return to some sort of status quo. Relationships almost never work because characters can't "age" and the "will they/won't they" drama is some of the easiest to write. The movie ends with the Hulk the new "king" of the planet, with a woman who loves (sorta) him, and the respect of a planet full of people.
Here's what happens next in the comics:
Followed by this:
So I'll admit I'm left confused since they really don't leave the Planet Hulk story open, unless they planned another movie that starts with "world blows up, Hulk gets angry, smashes everything again." Otherwise, well...
To put it plainly, what's the point? Was Planet Hulk meant to be the final animated movie starring the Hulk? Was it simply an attempt to test the waters again to see if people like the character before they made him more prominent in live action films again?
You know, there are other Hulk stories you could tell before pulling out the one that lead to him going to war with the entire planet Earth. Maybe you could do Future Imperfect, highly regarded as one of the best Hulk stories (and high up there on the best Marvel stories) of all time where he has to go into the future to fight his insane and evil future self, The Maestro?
Why not give something to lead in to this movie? If you don't want to involve Bruce Banner, you could start with a movie showing the two being separated, something that happened some time ago. It lead to the Hulk being a mindless rampaging monster with no real limit to his rage (or strength) and taking on Iron Man, Hercules, Thor, and Wonder Man. You could easily make a movie with those five punching each other for a while before Bruce has to come back, reunited with the Hulk... and THEN you can lead in with "oh, by the way, we're blasting you out into space."
As an adaption of a story, it's fine, but on its own I find myself more and more wondering "why?" Why make this story with no lead in and no chance for follow-up without it seeming forced? Not that they ever did follow it up, so, I guess that really was the "last" animated Hulk story. Congratulations, Hulk, you got your happy ending, roll credits.