HUGE potential. I'd say hardly any of the general public knows who Iron Man is, but the general public can't be looked to for knowledge of characters that haven't already had movies or shows. But Iron Man is one of the best possible superheroes to spin into a successful movie franchise. You have:
Wealthy billionaire playboy
Genius inventor
Corporate intrigue
Futuristic suits of armor (great CGI graphics and ridiculous action sequences, flying, feats of strength, etc)
Flawed hero (He's an alcoholic and depends on the armor for life support)
Semi-relevant current events (The interplay between big corporations and governments, arms dealing, weapons and their use in wars and geopolitics, medical technology, and even body modification)
Plus you have unlimited potential for different suits of armor for both Iron Man and his enemies, which means lots of marketing and merchandising capabilities. I can see well-imagined Iron Man action figures flying off the shelves if they're unique enough, as opposed to all the peg-warming Hulk and Superman Returns figures that all looked the same.
Iron Man is an incredible concept. Taking a Rennaissance Man along the lines of a Henry Ford, Albert Einstein, Bill Gates, etc. and letting him turn scientific wizardry loose on a concept designed to BUILD a hero is something that really ought to appeal broadly. The basic Iron Man origin has a Tom Clancy-esque sensibility, but never loses the humanity at the heart of the tale, and certainly never seemed to get bogged down in the technobabble.