The only reason I could see going out of your way to see Steamboy is if you really loved Akira. Personally, Akira was one of the first anime films I ever saw so it has a bit of a special place in my heart, even though I consider it highly overrated.

Obviously I saw Steamboy really close to the time when it first came out, and I was extremely excited about it. Sadly, I found it to be an incredible bore. I nearly fell asleep numerous times while watching it and about 3/4 of the way through I couldn't wait for it to be over. If it wasn't for the reputation Katsuhiro Ôtomo had from Akira, I doubt Steamboy would have even been localized to the U.S.

I say don't bother with it.