I say both sides are getting it all wrong.
Aside: I highly recommend watching Steamboy before proceeding with this, and before watching Steamboy, watching Laputa so as to understand the conventions that Otomo is subverting.
When compared to a movie similar in tone and subject, such as Miyazaki's Laputa: Castle in the Sky, it becomes clear that Katsuhiro Otomo has wrought a well-paced, gorgeously designed, lavishly animated, and wickedly subversive movie. On the surface, which all the critics are fixated on, this is a rote action movie that is executed strictly by the numbers. The formula goes something like this:
- A parentless, inventive young man meets a girl with a mysterious past and a talisman that is a key to enormous power.
- A pair of mysterious men show up and give chase to spectacular effect. The hero usually has a single wheel with engine inside of wheel vehicle. (see illustration)
- A band of toughs turn out to have hearts of gold and assist the heroes in their journey.
- A secret evil conspiracy emerges as the true villain.
- The secret conspiracy captures the girl and the talisman, and try to use them to control an ancient structure or vehicle of immense power.
- The villains are defeated and the ancient structure/vehicle is destroyed or made permanently inaccessible to normal hu-mans.
- The world is either a better place or exactly the way it was before things started.

For both incarnations of the Miyazaki steampunk adventure, viz. his own epic Laputa and the GAINAX television series The Secret of Blue Water, the world is restored to the status quo ante bellum: no secret oppressive conspiracies, no superweapons roving about. In Blue Water, the Eiffel Tower gets melted by a laser from a giant ancient flying saurcer, yet it is rebuilt the next year, and a time paradox is averted.
Steamboy flies in the face of this sort of ending: it portrays a series of events that cause the world to diverge radically from the timeline we know. That was the plan of the antagonist from the beginning, and that plan succeeded flawlessly. In a montage under the closing credits, we see the strange and terrifying face of this new world: paratroopers dropping over trenches, clashes of armed airships, and the titular hero unable to stop things. The main female character is shown as having grown up to be a redheaded air pilot with the smirk of Blue Water's Grandis. And all this happens before 1880!
Most alternate history anime puts the viewer in the middle of the "strange real world" and gradually reveals the point of chronological divergence. Gunparade March takes place in 1999, but posits a transdimensional invasion in 1945, just as Sakura Taisen takes place in the twenties after an anti-demonic Great War. (and yes, both of these were originally games.) Last Exile turns out to be a "crashed colony" exercise along the lines of Trigun. The alternative is to create a world with no ties to our own, as in the industrial fantasy of Laputa or just about any work of pure fantasy (Berserk or Lodoss, for that matter) or to make sure to keep things in our own timeline, as in Blue Water.
Steamboy, on the other hand, goes in a totally unexpected direction, creating a world that appears to be our own up to the very ending. The viewer expects a return to normalcy and historicity that never comes. The only clue that things are awry is the date given at the beginning. The main plot occurs in 1866, yet the actual Crystal Pavilion (and the Exhibition, for that matter) was dismantled in 1854. This is dismissively pointed out as an error on Otomo's part, yet with over ten years of work I doubt that this was accidental.
There is something indeed wrong with the 1866 portrayed in Steamboy: a source of limitless energy. The hero's father and grandfather have created a limitless energy source. Ostensibly an unbreakable vessel carrying hyperpressurized rare mineral water, it is a boiler the size of a basketball that needs no water, or alternately a Civil War era nuke analogue. In other words, the formulaic talisman of unbelievable power. It can power anything it is attached to, or more importantly, it can be used to fill the tanks of any steam powered device. Whoever has a Steam Ball can field armies of steam-powered armored infantry, steam tanks, and even steam ornithopters. And when the three Steam Balls are used together, it can propel a giant black tower (Steam Tower, of course) into the sky.
In the process of manufacturing the Steam Balls for an American shadow corporation, the O'Hara Foundation, the elder Lloyd Steam pushes forward, despite impending danger. As a result of his recklessness, his son, and hero Ray's father, Eddy Steam is scalded and disfigured, turning into a "Darth Steam" like a Victorian cyborg version of Akira's Colonel Shikishima. Lloyd claims science should only be used for humanity's betterment, Eddy claims science is power, and Ray is not sure who to follow. Thus we have a three-way father-son conflict. Adding to the conflict is that the selfish female lead Scarlett O'Hara is the heir apparent to the evil corporate conspiracy, and follows Ray Steam out of idle curiosity instead of the traditional need for protection. These are all twists on the conventions of steampunk anime in the past, and also point towards Otomo's unorthodox take on the genre.
Up until the end it is unclear who is using whom. The O'Hara Foundation wants to sell steam-powered engines of destruction to the highest bidder. At first it seems that Eddy Steam is being deceived into working on weapons for the rich, but in fact they are hapless businessmen that are subject to Eddy's plan to change the course of history. Steam Tower is the key to his plan.
Grandfather Lloyd Steam wants to use the power of the Steam Balls for peace, so he escapes his cell in Steam Tower and goes on a campaign of sabotage, planning to shoot Eddy in the head.
To his death in the end credits, Lloyd is unrepentant for creating the Steam Balls. He never regrets the order to continue, and never apologizes for disfiguring and maiming his own son for the pursuit of knowledge. He rationalized his decision to work on the flying fortress Steam Tower by building a system into it that would let it transform into a giant walking amusement park, complete with merry go round and Ferris wheel. And then he has the gall to damn his own son for creating steam powered weapons! Lloyd Steam is a sociopath, asserting his own moral superiority in pursuing knowledge while ignoring the consequences of his own actions.
In a scene where any other movie of this genre would have climaxed, Lloyd urges Ray to leave so he can self-destruct Steam Tower, foil Eddy's mad warmongering plans, and make sure that the Steam Balls are not used for war. But Ray screams that the tower is no longer over the Thames, but downown London, and they must use the third Steam Ball they have been protecting to bring Steam Tower up to full power.
Yet neither of them realize that, true to his word, Eddy has triumphed the moment Steam Tower took to the air. Once the world has seen that such things as this are possible, he proclaims, everyone will try to build new weapons of war. And true to his word, the world changes into something unrecognizable.
As a final point, Ray Steam and Scarlett escape by finding a steam-powered rocket suit that Eddy left for emergencies in the control room. This suit fits Ray perfectly. Perhaps he has fit the role that Eddy has planned for him all along.
I eagerly look forward to the sequel, which is already in production.
On to what everyone agrees on. The animation is perfect; Otomo's design work on both characters and mecha are perfection. There are some uncannily well done pans that are done; certainly a very cinematic anime.
The perfect production work and the subtle, clever writing makes this, in my opinion, the best anime I have ever seen, and possibly the best anime ever made. I found myself strangely reminded of the work of Alan Moore: both in the intricate alternate-Victoriana of The League of Extraordinary Gentlemen and the genre-deconstruction of Watchmen.
