I've really liked the job Julian McMahon has done as Doom. Very few people can play a convincing bad guy. Julian just has a charisma and charm to make you really like him even though he's the bad guy.
It's like Kevin Costner, in this new film Mr. Brooks. I just don't believe him as a bad guy. To me it's just Kevin Costner up on the screen. He's a better actor when he's in films more suited to him like Tin Cup, or the Untouchables.
I think McMahon has done a great job in both of these movies. Yeah it's a bit of a change from the comics, but I think it works on screen. They kept all the important parts, the self obsession, the hatred of Reed Richards, the incurable vanity.
And yes his genious is shown on par with Richards. While the movie doesn't explain too much, the fact is Doom learned how to track the Surfer first, and without any help from Sue.
The only reason Doom went to Richards, was his encounter with the Surfer let him know that he was too powerful to face alone.