I discovered the Iron Man anime by pure chance and had to watch it. There are plenty of reasons why the Iron Man character is perfect for a Japanese anime adaptation. For starters, Japanese excel at stories about people mounting various mechanical suits or machines that later on transform into humanoids. Let's think of Gundam, Voltron and the Mighty Morphing Rangers [though that example is a bit of pushing-my-luck]. On the same techno wave there is Megaman and Astro boy.
It's a definite that Japanese animators know their mecha and they don't waste their time. In the first episode, Tony Stark engages in a beautiful aerial scene and then into heavy combat with a suit gone rogue and then an alien-looking mechanical beast. The quality of is beyond all my expectations and the anime is stunning to watch. You can see for yourself. Here is the opening sequence, which pretty much sets the tone for the series:
On a different level, I don't think this anime will work for Westerners. Tony Stark loves his women, his liquor and a good boast. I haven't read enough of the comic series that feature him as a lead [I'm generally not interested in him as a character], but Stark's everything that the Japanese aren't. Most of their anime and manga production feature a lead, who wants to achieve something morally good and has no dark flaws such as alcoholism. Perhaps the lead will be too nice, too shy or too modest aka character traits that Tony Stark is far from. And this shows... His flirts are almost innocent. He's passive and well it's like watching Stark, but on sleeping pills. However, I don't want to sound like a mad fanboy [considering that I'm not] and do think that it will be interesting to see how the Japanese will re-invent Stark.