Ok, to start off, let me by saying I am a big fan of movies that are not liked ny the norm. Sometimes, they aren't even liked by anybody. Most people would call these bad movies. So I will simply state I like bad movies. A quick look at my movie shelf at home will tell you that. Hell, I sat through Ballistic: Ecks vs Sever. I tell you this to show you the amount of pain I will put myself through for a movie.
After 20 minutes of Speed Racer, I walked out. I've never done it before. I also got myself a refund. I don't understand how you can make racing boring. The method the used of showing you the race and then giving you background was more annoying than rush-inducing. The traffic I sat in going home was more exciting. The way it ended was really predictable as well.
Also, it seems like they tried to make the goofy conversations from cartoon (Of which I am a big fan) serious. I give to you the pancake conversation as my evidence. These conversations are dragging when not followed by the hearty HAHA! from the cartoon.
In closing, just go see Iron Man again, fanboy. IT's worth the money.