Why It Sucked:
Steve Rogers from the comics was an artist at heart, sure, but he was also prepared to fight for his country even before he was loaded up with super steroids. He was a superhero who could have genuinely been considered a true hero pre-powers. The writers of 1971's Captain America thought this was so inspiring that they decided to leave it out completely and focus on the whiny, artsy side.
"I'll tell you what Red Skull hurt the most: my feelings...
One of the other great things about Captain America was that he willingly volunteered to take the super serum, because it meant he would be better at doing what he loved (punching Nazis). In this movie, the serum is given to Rogers without his consent, and he reluctantly decides to fight crime after it turns out he has superpowers. Basically, everything that made Steve Rogers honorable and respectable was removed and replaced with... art? A helmet? We don't even know. A see-through shield?
Now, the good Captain's transportation doesn't really come up too often in the comics, so we can't say the filmmakers behind this movie screwed it up. Still, we feel fairly secure in the belief that he would not roll around in a blue GMC Van that shoots an almost useless motorcycle out of the back.
And finally, the costume. Instead of just copying the already awesome comic book costume, they apparently hired a costume designer who'd never heard of Steve Rogers (or America), and said, "Make an American motorcycle superhero in 10 minutes or you're fired."
Why You've Never Seen It:
This movie was only made for TV and the general reaction of the public was so collectively indifferent, that they decided to make a terrible sequel that received a similar amount of disinterest.